HoldsUp

Kerry Courneya

Kerry Courneya, PhD, is a researcher studying the effects of exercise and physical activity in cancer care and survivorship. His research evaluates the feasibility, safety, and efficacy of various structured exercise interventions—such as aerobic, resistance, and high-intensity interval training—in patients with cancers including breast, colorectal, prostate, bladder, and endometrial cancer. His publications investigate outcomes related to cancer survival, treatment tolerance, health-related fitness, quality of life, and the economics of exercise interventions.

61 claims checked on air: 1 contradicted 2 overstated 54 supported 4 unverified

What they said on air - supported

6 citing their own research

0:00:00supportedvery lowThe Science of Exercise for Cancer | Kerry Courneya, PhD

Exercise increases vascular shear stress, which reduces the survival rate of circulating tumor cells shed into the bloodstream.

"And there's some really interesting research suggesting that if you exercise while the tumors are shedding these circulating tumor cells, those circulating tumor cells are less likely to survive because of the increased shear stress. So when blood's flowing through the vasculature, it's under a certain amount of pressure, but of course that's dramatically increased when you exercise, and these circulating tumor cells are far more likely to die and not survive that journey if you're exercising." (said at 0:00:00)

Preclinical in vitro research supports the claim that exercise-level hemodynamic shear stress reduces the survival of circulating tumor cells (CTCs). In a microfluidic circulatory system testing shear stress levels corresponding to intensive exercise (60 dynes/cm²) versus resting human arterial conditions (15 dynes/cm²), exercise-level shear stress caused rapid necrosis in more than 90% of tested CTCs within 4 hours, and triggered apoptosis in remaining surviving cells. Because this mechanism has been demonstrated in microfluidic models rather than directly tracked in vivo in exercising human cancer patients, the certainty of evidence remains very low.

0:03:06supportedhighThe Science of Exercise for Cancer | Kerry Courneya, PhD

Approximately 2 million Americans are diagnosed with cancer each year.

"So every year in the US, about 2 million Americans are diagnosed with cancer" (said at 0:03:06)

Annual nationwide cancer surveillance data from the American Cancer Society and central cancer registries report approximately 2 million new cancer diagnoses annually in the United States (1,958,310 projected in 2023; 2,001,140 in 2024; and 2,041,910 in 2025).

0:03:12supportedhighThe Science of Exercise for Cancer | Kerry Courneya, PhD

The American Cancer Society estimates that about 40% of cancer cases in the United States could be prevented through optimal lifestyle practices.

"and the American Cancer Society estimates that about 40% of those cancers could be prevented if everybody followed sort of the optimal lifestyle suggestions that they make. So we could reduce those 2 million diagnoses every year to about 1.2 million." (said at 0:03:12)

The claim accurately reflects epidemiological estimates published by researchers at the American Cancer Society. Nationwide analyses of US adults aged 30 and older estimated that 40.0% of incident cancer cases in 2019 (and 42.0% in 2014) were attributable to potentially modifiable risk factors, including tobacco smoking, excess body weight, alcohol consumption, physical inactivity, poor diet, ultraviolet radiation, and cancer-associated infections.

0:03:45supportedhighThe Science of Exercise for Cancer | Kerry Courneya, PhD

Between 80% and 85% of the US population does not smoke.

"Assuming you're not smoking, which is 80 to 85% of the American population" (said at 0:03:45)

Nationally representative surveillance data from the Centers for Disease Control and Prevention's National Health Interview Survey (NHIS) show that approximately 80% to 88% of US adults do not smoke or use tobacco products. In recent years, adult cigarette smoking prevalence was estimated at 14.0% in 2019, 12.5% in 2020, and 11.5% in 2021 (meaning roughly 86% to 88.5% do not smoke cigarettes). When considering any commercial tobacco product (combustible and non-combustible), prevalence ranged from 18.7% to 20.8% (meaning 79.2% to 81.3% do not use tobacco). The stated estimate of 80% to 85% is fully consistent with these national figures.

0:03:50supportedmoderateThe Science of Exercise for Cancer | Kerry Courneya, PhD

Obesity is the second-leading lifestyle risk factor for developing cancer after smoking.

"obesity is actually the second on the list of risk factors for developing cancer." (said at 0:03:50)

Epidemiological analyses evaluating population attributable fractions (PAFs) for modifiable lifestyle risk factors consistently identify excess body weight (overweight and obesity) as the second-largest modifiable contributor to cancer incidence after tobacco smoking. In large national burden-of-cancer analyses, tobacco smoking accounts for the largest proportion of preventable cancers, followed closely by overweight and obesity (accounting for approximately 5% to 7% of all incident cancer cases across major cancer types).

0:04:20supportedmoderateThe Science of Exercise for Cancer | Kerry Courneya, PhD

Exercise has been shown to reduce the risk of 8 to 10 specific cancer types, including colon, breast, endometrial, stomach, and esophageal cancer.

"and exercise has been shown to reduce the risk of, you know, maybe 8 to 10 of those cancers. There's over 100 different types of cancer, so it's a very complicated disease, all different cancer types. But we now have evidence suggesting that exercise will lower the risk of getting some of those cancers, particularly colon cancer, breast cancer, endometrial cancer, and several other cancers as well, such as stomach cancer, esophageal cancer, and a few others." (said at 0:04:20)

Epidemiological pooled analyses and consensus guidelines consistently demonstrate that physical activity/exercise is associated with a reduced risk of multiple specific cancer types (typically cited as 7 to 13 cancer sites). In a pooled analysis of 1.44 million adults from 12 prospective cohorts (Moore et al., 2016), higher leisure-time physical activity was associated with statistically significant risk reductions for 13 cancer types, including esophageal adenocarcinoma, gastric cardia (stomach), endometrial, colon, and breast cancers (with 10 remaining significant after BMI adjustment). An American College of Sports Medicine roundtable consensus (Patel et al., 2019) similarly concluded that physical activity has strong preventive evidence for breast, colon, endometrial, kidney, bladder, esophageal, and stomach cancers.

0:04:30supportedhighThe Science of Exercise for Cancer | Kerry Courneya, PhD

There are over 100 distinct types of cancer.

"There's over 100 different types of cancer, so it's a very complicated disease, all different cancer types." (said at 0:04:30)

Major cancer organizations, including the National Cancer Institute (NCI) and the World Health Organization (WHO), classify cancer not as a single disease but as an umbrella term encompassing more than 100 distinct histological and anatomical disease types and subtypes. Large-scale pan-cancer genomic analyses and oncological literature consistently reference more than 100 distinct tumor types.

0:06:00supportedhighThe Science of Exercise for Cancer | Kerry Courneya, PhD

Public health guidelines recommend approximately 150 minutes per week of moderate-to-vigorous intensity aerobic exercise.

"And, you know, the general recommendation is the public health guidelines of about 150 minutes per week of moderate-to-vigorous intensity aerobic exercise." (said at 0:06:00)

Major public health guidelines, including the World Health Organization (WHO) Guidelines on Physical Activity and Sedentary Behaviour and the US Physical Activity Guidelines for Americans, recommend that adults accumulate at least 150 to 300 minutes of moderate-intensity aerobic physical activity, 75 to 150 minutes of vigorous-intensity activity, or an equivalent combination per week for substantial health benefits.

0:06:20supportedmoderateThe Science of Exercise for Cancer | Kerry Courneya, PhD

Muscular strength training can lower the risk of developing certain types of cancer.

"Some evidence has suggested muscular strength training can lower the risk of some of these cancers as well" (said at 0:06:20)

Systematic reviews and meta-analyses of observational cohort studies show that muscle-strengthening activities are associated with a reduced risk of total cancer incidence and mortality, as well as specific site cancers such as lung and kidney cancer. The speaker's statement that "some evidence has suggested muscular strength training can lower the risk of some of these cancers" accurately reflects the current epidemiological literature.

0:09:14supportedhighThe Science of Exercise for Cancer | Kerry Courneya, PhD

Exercise lowers cancer risk independently of obesity status, showing risk reductions even in individuals with a BMI over 30 who do not lose weight.

"So one of the mechanisms how exercise might lower the risk is through managing obesity, but what we also see is exercise lowers the risk of cancer regardless of your obesity status. So we can do the subgroup analysis of those who are BMI above 30, overweight category, healthy weight; all of them show a reduction. So obesity is not the only mechanism by which exercise is lowering the risk. So even if you're obese and you don't lose weight, exercise can help you lower the risk of developing cancer." (said at 0:09:14)

Large-scale prospective epidemiological studies confirm that higher physical activity levels are associated with reduced cancer risk across different body mass index (BMI) categories, including in individuals classified as overweight or obese. In a pooled meta-analysis of 1.2 to 1.44 million adults (Moore et al., 2016), physical activity was inversely associated with 13 different cancer types, and these inverse associations were observed regardless of body size (normal weight, overweight, or obese). Subsequent prospective cohort studies (e.g., UK Biobank analysis) similarly report that high physical activity attenuates the elevated cancer hazard associated with overweight and obesity.

0:09:40supportedmoderateThe Science of Exercise for Cancer | Kerry Courneya, PhD

Exercise reduces the risk of lung cancer even among individuals who actively smoke.

"We even see this with smokers, so we can break them into sort of the smokers and the non-smokers with lung cancer risk, and even those who are smoking, exercise will help them lower the risk." (said at 0:09:40)

Meta-analyses of prospective cohort studies consistently demonstrate an inverse association between physical activity and lung cancer risk among current and former smokers. In a systematic review and meta-analysis evaluating cohort studies stratified by smoking status (PMID: 27502335), higher levels of physical activity were associated with a significant reduction in lung cancer risk among current smokers (summary relative risk [RR] = 0.80, 95% CI: 0.70–0.90) and former smokers (RR = 0.68, 95% CI: 0.51–0.90). Another meta-analysis restricted to smokers across 7 cohort studies found a similar risk reduction (RR = 0.82, 95% CI: 0.77–0.87; PMID: 23528254). Because these findings derive from observational studies, residual confounding by smoking intensity or duration cannot be completely ruled out, but the observed protective association is consistent across multiple large datasets.

0:10:05supportedhighThe Science of Exercise for Cancer | Kerry Courneya, PhD

Carrying BRCA gene mutations carries approximately an 80% lifetime risk of developing breast cancer.

"You know, the BRCA genes you talked about, there is like an 80% chance of getting breast cancer and very high with ovarian and some of these other ones" (said at 0:10:05)

Large prospective cohort studies and genetic epidemiology show that female carriers of pathogenic BRCA1 and BRCA2 variants face a substantial lifetime risk of developing breast cancer. A landmark prospective cohort study (Kuchenbaecker et al., 2017) tracking nearly 10,000 carriers estimated cumulative breast cancer risk to age 80 at 72% (95% CI, 65%–79%) for BRCA1 and 69% (95% CI, 61%–77%) for BRCA2 carriers, with risks reaching up to ~80% in women with strong family histories or specific mutation locations. The speaker's statement of 'like an 80% chance' is a common and accurate approximation of lifetime risk.

0:10:45supportedmoderateThe Science of Exercise for Cancer | Kerry Courneya, PhD

Exercise lowers the risk of developing cancer even in individuals who have a family history of cancer.

"If someone's got a family history, we've seen some of the studies look at that, trying to look at kind of—and just do it as you say—by family history, a very simple way of looking at it, and we do find that exercise lowers the risk of developing some of these cancers even in those who have a family history." (said at 0:10:45)

Epidemiological cohort studies confirm that physical activity is associated with a lower risk of certain cancers, such as postmenopausal breast cancer, even among individuals with a family history of the disease. In the prospective Sister Study cohort of over 50,000 women who had a sister with breast cancer, higher levels of physical activity were significantly associated with a 25% reduction in postmenopausal breast cancer risk (hazard ratio 0.75), an association that did not differ based on the extent of family history.

0:12:15supportedmoderateThe Science of Exercise for Cancer | Kerry Courneya, PhD

There is a dose-response relationship between exercise volume and cancer risk reduction, where more physical activity correlates with greater risk reduction.

"Yeah, so what we see in the cancer prevention literature is there is a dose-response association, as we say. So that means the more exercise you do, the greater the risk reduction." (said at 0:12:15)

Large-scale prospective cohort studies and meta-analyses demonstrate an inverse dose-response relationship between physical activity volume and cancer risk. A comprehensive dose-response meta-analysis of prospective cohorts including over 30 million participants (Garcia et al., 2023) showed that higher volumes of non-occupational physical activity are associated with lower incidence of total cancer as well as multiple site-specific cancers, with the steepest risk reductions observed between 0 and 8.75 mMET-hours/week (equivalent to the standard guideline of 150 minutes/week of moderate-to-vigorous activity) and diminishing marginal reductions at higher volumes. Similarly, a pooled analysis of 1.44 million adults across 12 cohorts (Moore et al., 2016) found that higher leisure-time physical activity was associated with lower risks across 13 different cancer types.

0:14:48supportedmoderateThe Science of Exercise for Cancer | Kerry Courneya, PhD

Cancer risk reduction benefits from exercise continue to accrue up to about 300 minutes per week, after which the curve plateaus.

"So the general recommendation is actually 150 to 300 minutes. So, you know, 150 we kind of view as the minimum to getting these benefits, and then those benefits will continue to accrue up to about 300 minutes, and then the curves kind of plateau after that." (said at 0:14:48)

Large-scale pooled cohort studies evaluating physical activity dose-response relationships support the claim. Public health guidelines define 150 to 300 minutes per week of moderate-intensity physical activity (equivalent to 7.5 to 15 MET-hours/week) as the recommended target. Epidemiological analyses show that risk reductions for multiple cancer types and cancer mortality accrue across this range, with the curve flattening or demonstrating diminishing additional returns beyond 15 MET-hours/week (approximately 300 minutes).

0:15:48supportedhighThe Science of Exercise for Cancer | Kerry Courneya, PhD

Exercise guidelines treat vigorous-intensity exercise as conferring approximately double the credit or benefit per minute compared to moderate-intensity exercise.

"And generally the guideline is just sort of double-weight vigorous minutes. So when we say it can be 150 minutes of moderate or 75 minutes of vigorous, you kind of get double credit for the vigorous-intensity exercise, or any combination of the two." (said at 0:15:48)

Major public health guidelines—including the World Health Organization (WHO) Guidelines on Physical Activity and Sedentary Behaviour and the U.S. Physical Activity Guidelines for Americans—recommend that adults obtain 150 to 300 minutes of moderate-intensity aerobic activity per week, 75 to 150 minutes of vigorous-intensity activity, or an equivalent combination of both. In these guidelines, 1 minute of vigorous-intensity physical activity is formally treated as equivalent to 2 minutes of moderate-intensity physical activity (a 2:1 weighting).

0:17:21supportedmoderateThe Science of Exercise for Cancer | Kerry Courneya, PhD

Studies demonstrate that pre-diagnosis exercise is associated with improved post-diagnosis cancer survival outcomes, independent of post-diagnosis exercise.

"And so there is some studies that link both pre-diagnosis exercise and post-diagnosis exercise to better cancer outcomes, and some of those studies show that, yes, even the amount of exercise you were doing before diagnosis might improve your outcomes after diagnosis, independent of what you do after diagnosis." (said at 0:17:21)

Large meta-analyses of prospective observational cohort studies confirm that both pre-diagnosis and post-diagnosis physical activity are significantly associated with reduced all-cause and cancer-specific mortality in cancer survivors (notably breast and colorectal cancers). Several cohorts evaluating activity before and after diagnosis have demonstrated that higher baseline pre-diagnostic physical activity confers survival advantages even after accounting for post-diagnosis activity levels and changes.

0:20:20supportedmoderateThe Science of Exercise for Cancer | Kerry Courneya, PhD

In the general surgical literature, prehabilitation exercise programs prior to major surgery reduce surgical complications and shorten hospital length of stay.

"In the general literature, these programs have been shown to be effective for patients going onto surgery, onto a major surgery, and show that they have fewer complications from the surgery, shorter hospital stay." (said at 0:20:20)

Multiple systematic reviews and meta-analyses of randomized controlled trials demonstrate that exercise-based and multimodal prehabilitation programs before major elective surgery significantly reduce postoperative complications and shorten hospital length of stay. For example, a comprehensive network meta-analysis of 186 randomized controlled trials (15,684 participants) by BMJ (2025) reported that isolated exercise prehabilitation significantly reduced postoperative complications (odds ratio [OR] 0.50, 95% CI 0.39 to 0.64) and shortened hospital stay by -0.93 days (95% CI -1.27 to -0.58). Combined exercise and nutrition prehabilitation reduced stay by -1.22 days (95% CI -2.54 to 0.10), while combined exercise and psychosocial intervention reduced stay by -2.44 days (95% CI -3.85 to -1.04). While individual trial certainty varies due to open-label designs or imprecision across individual study components, the overall body of evidence consistently demonstrates beneficial effects on complication rates and hospital stay across major surgical populations.

0:22:28supportedhighThe Science of Exercise for Cancer | Kerry Courneya, PhD

Nutritional and supplement interventions have shown limited success in treating or reversing cancer cachexia.

"they've attempted to address it mostly with nutritional interventions and supplement types of interventions, but not had great success." (said at 0:22:28)

Clinical practice guidelines and systematic reviews confirm that nutritional and dietary supplement interventions alone have demonstrated limited success in halting or reversing cancer cachexia. Because cancer cachexia involves complex systemic metabolic derangements and pro-inflammatory signaling rather than simple caloric starvation, conventional oral nutritional supplements, dietary counseling, and aggressive feeding modalities generally produce modest or no sustained improvements in lean muscle mass, clinical outcomes, or survival.

0:23:30supportedmoderateThe Science of Exercise for Cancer | Kerry Courneya, PhD

In lung cancer, patients with obesity/higher BMI have been observed in studies to experience longer survival than normal-weight patients.

"So we've seen that in a few of the studies, say with lung cancer, that once you're diagnosed with lung cancer, patients who are actually larger, more obese, have a little bit longer survival." (said at 0:23:30)

Multiple systematic reviews and meta-analyses have documented an observational phenomenon often called the 'obesity paradox' in lung cancer, wherein patients with overweight or obesity demonstrate longer survival compared to normal-weight patients. For example, a meta-analysis of 25 observational studies in surgical lung cancer patients found that higher BMI was significantly associated with improved long-term survival (HR: 0.69, 95% CI: 0.56–0.86). Similarly, a meta-analysis of advanced non-small cell lung cancer patients treated with immune checkpoint inhibitors showed that overweight and obese patients had prolonged overall survival compared to normal-weight patients (HR: 0.818, 95% CI: 0.741–0.902).

0:24:31supportedhighThe Science of Exercise for Cancer | Kerry Courneya, PhD

Sarcopenic obesity is a medical phenotype where high levels of body fat co-occur with low skeletal muscle mass.

"There is this phenomenon we call sarcopenic obesity. So, yeah, there's high rates of obesity, but those people have fairly low lean body mass as well. So there's different kind of phenotypes, if you will, of the obesity" (said at 0:24:31)

The speaker's statement accurately reflects the established clinical and scientific definition of sarcopenic obesity. Major international guidelines, including the joint consensus statement from the European Society for Clinical Nutrition and Metabolism (ESPEN) and the European Association for the Study of Obesity (EASO), formally define sarcopenic obesity as the co-existence of excess adiposity (obesity) and reduced skeletal muscle mass and/or muscle function (sarcopenia).

0:30:11supportedhighThe Science of Exercise for Cancer | Kerry Courneya, PhD

Physical activity guidelines no longer recommend a minimum duration of at least 10 minutes per exercise bout for health benefits.

"And as I mentioned, you know, we're no longer recommending this at least 10-minute duration as the minimum of an exercise break. So if it's moderate intensity and you're able to accumulate it in a few minutes here and a few minutes there, there could be beneficial effects of that type of exercise." (said at 0:30:11)

The second edition of the Physical Activity Guidelines for Americans (released in 2018) officially removed the previous requirement that aerobic physical activity had to occur in bouts of at least 10 minutes to count toward recommended physical activity targets. Updated epidemiological evidence showed that moderate-to-vigorous physical activity accumulated in shorter, sporadic durations confers health and mortality risk-reduction benefits comparable to bouted activity.

0:32:45supportedhighThe Science of Exercise for Cancer | Kerry Courneya, PhD

There are over 100 different types of chemotherapy drugs and dozens of approved immunotherapies for cancer.

"There's over 100 different types of chemotherapy drugs with all different side effects. There's dozens and dozens of immunotherapies that are now approved." (said at 0:32:45)

The speaker's assertion is accurate. Pharmacological classifications and regulatory approvals by agencies such as the FDA and EMA document well over 100 distinct cytotoxic chemotherapy agents (spanning classes such as alkylating agents, antimetabolites, mitotic inhibitors, topoisomerase inhibitors, and antitumor antibiotics). Furthermore, dozens of cancer immunotherapies are currently approved for clinical use across multiple modalities, including immune checkpoint inhibitors (e.g., targeting PD-1, PD-L1, CTLA-4, LAG-3), chimeric antigen receptor (CAR) T-cell therapies, bispecific T-cell engagers (BiTEs), cytokines (interferons, interleukins), oncolytic virus therapies, and cancer vaccines.

0:38:19supportedhighThe Science of Exercise for Cancer | Kerry Courneya, PhD

Cancer patients who exercise during chemotherapy report lower fatigue than patients who rest.

"And so some of the early studies started showing the patients that rested during chemotherapy actually reported more fatigue than the patients who exercise... And we've demonstrated that consistently in the exercise oncology field that patients who exercise going through these treatments have lower fatigue." (said at 0:38:19)

The claim is supported by high-certainty evidence from randomized controlled trials and systematic reviews/meta-analyses (such as Cochrane reviews). Evidence demonstrates that exercise during and after cancer therapy (including chemotherapy) significantly reduces cancer-related fatigue compared to control/usual care (rest).

0:39:15supportedhighThe Science of Exercise for Cancer | Kerry Courneya, PhD

Exercise improves sleep quality and reduces anxiety and depression in cancer patients undergoing treatment.

"The other benefits that have been shown definitively are improvements in sleep quality... And exercise has been shown to benefit sleep quality, reduce some of the anxiety associated with cancer, depression levels, and some of these other side effects as well." (said at 0:39:15)

Extensive randomized controlled trial evidence and international clinical consensus guidelines confirm that structured exercise improves sleep quality and significantly reduces symptoms of anxiety and depression in cancer patients during and after treatment.

0:40:20supportedmoderateThe Science of Exercise for Cancer | Kerry Courneya, PhD

Studies show cancer patients who exercise during chemotherapy complete more of their chemotherapy with fewer dose reductions and delays.

"And so some of these studies have actually shown that it's the patients who exercise during chemotherapy that end up completing more of their chemotherapy. They have fewer reductions in the chemotherapeutic drugs and fewer delays, and that portends a better outcome, a higher chance at cure, and a lower risk of recurrence." (said at 0:40:20)

Multiple randomized controlled trials and cohort studies support the claim that exercise during chemotherapy can reduce premature treatment discontinuation and improve relative dose intensity (fewer dose reductions and delays), particularly in breast cancer patients receiving anthracycline-based regimens. For example, the randomized BENEFIT trial found that both aerobic and resistance training significantly reduced premature discontinuation of neoadjuvant chemotherapy (OR = 2.34), and another randomized trial observed significantly higher chemotherapy relative dose intensity among patients receiving anthracycline regimens in the exercise arm compared with usual care (77% vs. 57%). However, systematic reviews note that while supervised, moderate-to-high intensity exercise frequently shows positive associations with treatment completion, results remain somewhat heterogeneous across different cancer types and trial designs.

0:41:00supportedmoderateThe Science of Exercise for Cancer | Kerry Courneya, PhD

Epidemiological studies show that cancer patients who report more exercise have a lower risk of disease recurrence and a lower risk of dying from cancer.

"but also these epidemiological studies showing that cancer patients who report more exercise seem to have a lower risk of recurrence of the disease and a lower risk of dying from the cancer many years down the road." (said at 0:41:00)

Numerous prospective epidemiological cohort studies and systematic reviews demonstrate that cancer patients (particularly those diagnosed with breast and colorectal cancers) who report higher levels of physical activity post-diagnosis have significantly reduced risks of cancer recurrence and cancer-specific mortality. While observational data are subject to residual confounding and potential reverse causation, the speaker accurately described the findings of epidemiological research.

0:42:25supportedhighThe Science of Exercise for Cancer | Kerry Courneya, PhD

In a clinical trial by Kerry Courneya's group, the resistance training group completed more chemotherapy than the aerobic exercise or usual care groups, gaining over a kilogram of lean muscle.

"In one of the studies that we did, it was actually the weight training group that completed more of their chemotherapy compared to the aerobic exercise group or the usual care group. And so this weight training group was able to put on over a kilogram of lean muscle while they were on chemotherapy" (said at 0:42:25)

In the multicenter randomized Supervised Trial of Aerobic versus Resistance Training (START) led by Kerry Courneya and colleagues, 242 breast cancer patients receiving adjuvant chemotherapy were assigned to usual care, aerobic exercise, or resistance exercise. The resistance training group demonstrated a significantly higher chemotherapy completion rate compared to usual care (P = 0.033) as well as significant gains in lean body mass (P = 0.015) and muscular strength.

0:43:25supportedhighThe Science of Exercise for Cancer | Kerry Courneya, PhD

The CARE trial examined high-dose aerobic exercise (150 min/week vigorous), moderate-dose aerobic exercise (75 min/week vigorous), and combined aerobic and resistance exercise in breast cancer patients.

"Yes, we did one trial we call the CARE trial, which stands for Combined Aerobic and Resistance Exercise in breast cancer patients. And we did find some additional benefits. We did a high dose of aerobic exercise, we did a moderate dose of aerobic exercise, and then we did a combined aerobic and resistance exercise." (said at 0:43:25)

The Combined Aerobic and Resistance Exercise (CARE) trial was a multicenter randomized controlled trial in 301 breast cancer patients initiating chemotherapy. Participants were assigned to three weekly supervised exercise sessions consisting of either a standard dose of aerobic exercise (25–30 min/session, totaling ~75–90 min/week), a higher dose of aerobic exercise (50–60 min/session, totaling ~150–180 min/week), or a combined aerobic and resistance exercise intervention (50–60 min/session).

0:45:45supportedvery lowThe Science of Exercise for Cancer | Kerry Courneya, PhD

Preclinical studies show that exercise improves blood vessel density and quality in primary tumors, enhancing chemotherapy delivery and tissue oxygenation.

"What they were able to show in these exercise studies is that exercise improves the quality of these blood vessels and the density of these blood vessels. And while you're improving the quality of these blood vessels, what that improved was chemotherapy delivery to the tumor, so it improved the delivery of the drugs to the tumor. What it also does is improve perfusion to the tumor, and these tumors become better oxygenated." (said at 0:45:45)

Preclinical animal models have demonstrated that aerobic exercise can induce tumor vascular normalization, increasing microvessel density, patency, and tumor perfusion, which diminishes intratumoral hypoxia and enhances chemotherapy delivery and efficacy. A 2021 meta-analysis of preclinical studies found regular exercise significantly increased tumor vascularization, improved tumor perfusion, and attenuated intratumoral hypoxia. Individual murine studies similarly demonstrated that exercise-induced vascular remodeling improves chemotherapeutic drug delivery. However, evidence remains largely confined to animal models with notable methodological heterogeneity across studies, and clinical translation in humans remains under investigation.

0:46:55supportedmoderatetheir own paperThe Science of Exercise for Cancer | Kerry Courneya, PhD

In a study of rectal cancer patients undergoing neoadjuvant chemoradiation, patients who exercised were more likely to achieve a complete pathological response prior to surgery.

"So in actual studies with patients, we did a study in rectal cancer patients, and the treatment for them is a combination of chemoradiation therapy prior to having the tumor surgically removed 12 weeks later. So they want to shrink and try and eliminate that tumor. And what we found is the patients who exercised while getting this chemoradiation therapy were more likely to have a complete response, meaning the tumors were completely gone prior to having the surgery." (said at 0:46:55)

The speaker's research group conducted the EXERT phase II randomized controlled trial (n = 36) evaluating supervised and home-based exercise in rectal cancer patients undergoing neoadjuvant chemoradiotherapy (NACRT) prior to surgery. In this trial, 56% (10 of 18) of patients in the exercise arm achieved a pathologic complete response or near complete response (pCR/near pCR) compared to 18% (3 of 17) in the usual care arm (P = .020). Because this was a small preliminary phase II trial, authors noted that larger confirmatory trials are required.

0:48:15supportedvery lowThe Science of Exercise for Cancer | Kerry Courneya, PhD

Increased hemodynamic shear stress during exercise can kill circulating tumor cells in the vasculature.

"And there's some really interesting research suggesting that if you exercise while the tumors are shedding these circulating tumor cells, those circulating tumor cells are less likely to survive because of the increased shear stress. So when blood's flowing through the vasculature, it's under a certain amount of pressure, but of course that's dramatically increased when you exercise, and these circulating tumor cells are far more likely to die and not survive that journey if you're exercising." (said at 0:48:15)

The claim accurately reflects preclinical research demonstrating that hemodynamic shear stress levels corresponding to intensive exercise destroy circulating tumor cells (CTCs). In a microfluidic circulatory model, shear stress of 60 dyn/cm² (achievable during exercise) killed significantly more CTCs via necrosis and subsequent apoptosis than resting shear stress (15 dyn/cm²). Because this evidence is derived from in vitro microfluidic models rather than clinical human trials, certainty is very low.

0:48:47supportedhighThe Science of Exercise for Cancer | Kerry Courneya, PhD

Exercise reduces levels of insulin and insulin-like growth factor (IGF), which promote cancer cell growth and division.

"The metabolic effects of exercise, such as reducing insulin and IGF, these are all things that help cancer cells grow and divide more rapidly." (said at 0:48:47)

Exercise has been shown in multiple systematic reviews and meta-analyses of randomized controlled trials to lower circulating fasting insulin, improve insulin sensitivity, and modulate components of the insulin-like growth factor (IGF) axis in cancer survivors and healthy adults. In turn, elevated insulin and IGF signaling pathways act as mitogens that stimulate cancer cell proliferation, survival, and tumor progression.

0:49:20supportedmoderateThe Science of Exercise for Cancer | Kerry Courneya, PhD

Exercise stimulates the immune system by increasing natural killer cell count and cytotoxicity, as well as T-cell and B-cell immunosurveillance against cancer cells.

"This was stimulating the immune system and improving natural killer cell cytotoxicity, the number of natural killer cells, the number of T cells and B cells that were all doing immunosurveillance of these cancer cells." (said at 0:49:20)

Published experimental trials and translational oncology studies confirm that acute exercise mobilizes cytotoxic immune cells into the peripheral bloodstream, notably natural killer (NK) cells and cytotoxic CD8+ T cells (and to a lesser degree B cells), via catecholamine-driven beta-2-adrenergic receptor signaling and hemodynamic shear stress. Furthermore, exercise has been demonstrated to transiently augment NK cell cytotoxic activity against tumor targets and enhance immune cell trafficking and immunosurveillance into tumor microenvironments.

0:51:03supportedvery lowThe Science of Exercise for Cancer | Kerry Courneya, PhD

Preclinical mouse models demonstrate that exercise increases the infiltration and numbers of T cells and natural killer cells within tumors.

"So that's been demonstrated in those preclinical mouse models. So they've shown that the mice that exercise will have higher numbers of T cells, natural killer cells within the tumor itself. So that improved blood flow allows everything to get into the tumor in order to be able to kill it." (said at 0:51:03)

Preclinical murine studies directly support the claim. In multiple mouse tumor models, voluntary exercise training significantly enhanced intratumoral infiltration and mobilization of natural killer (NK) cells (via epinephrine and IL-6 signaling) as well as CD8+ T cells (via CXCR3 signaling), alongside vascular normalization and improved perfusion. Because the available evidence consists of preclinical animal models, certainty is rated as very low.

0:51:35supportedmoderateThe Science of Exercise for Cancer | Kerry Courneya, PhD

Very high levels of exercise, such as marathon running or triathlon training, can cause immunosuppression.

"Now, exercise, to your point, can be immunosuppressive as well, right? We know these very high levels of exercise, the kind of triathletes and the marathon runners, right, it can cause immunosuppression." (said at 0:51:35)

Extensive research in exercise immunology confirms that acute, high-intensity endurance events—such as marathons and ultra-endurance training—are associated with transient post-exercise alterations in immune function and an increased incidence of upper respiratory tract infection symptoms. While classic literature and narrative reviews describe a post-exercise 'open window' of transient immunosuppression, recent immunologic evidence offers additional context, suggesting that post-exercise drops in circulating immune cells may partially reflect cell redistribution to tissues to enhance surveillance rather than outright immune dysfunction.

0:54:20supportedlowThe Science of Exercise for Cancer | Kerry Courneya, PhD

A human study demonstrated that an aerobic exercise intervention reduced circulating tumor cell levels.

"The one study that's been done in humans showing that exercise improves or reduces circulating tumor cells was an aerobic exercise program, but in theory, both should work." (said at 0:54:20)

A randomized pilot study in 23 patients with resected stage I–III colon cancer evaluated a 6-month aerobic exercise intervention (150 or 300 min/week vs. usual-care control). It found statistically significant reductions in circulating tumor cells (CTCs) in both aerobic exercise arms compared to baseline, while the control group showed no significant change. A subsequent 12-week randomized trial (n=60) found that aerobic exercise did not produce a statistically significant overall group-level reduction in CTCs, though adherence was negatively correlated with CTC counts.

0:59:47supportedhighThe Science of Exercise for Cancer | Kerry Courneya, PhD

A recently published study evaluated a blood-based test for colon cancer screening that showed approximately 80% sensitivity and 90% specificity.

"Just reading a study today in colon cancer, they've got a blood test now out for colon cancer, they're comparing it to colonoscopy because that's the gold standard way we detect, and it is fairly effective. It was like 80% sensitivity and 90% specificity, but they still were not recommending that for the general population." (said at 0:59:47)

The speaker accurately describes the results of the 2024 ECLIPSE clinical validation study published in The New England Journal of Medicine (Chung et al.). Evaluating a cell-free DNA blood-based test compared to screening colonoscopy in 7,861 average-risk participants, the test demonstrated an 83.1% sensitivity for colorectal cancer and an 89.6% to 89.9% specificity for advanced neoplasia or non-neoplastic findings. The study also noted a low sensitivity (13.2%) for advanced precancerous lesions, which contextualizes why blood tests do not fully replace colonoscopy for primary cancer prevention.

1:04:24supportedmoderateThe Science of Exercise for Cancer | Kerry Courneya, PhD

In cancer prevention epidemiology, physical activity shows the strongest protective associations with colon and breast cancers, but little association with rectal or prostate cancers.

"And you know, when you think on the prevention side of things, the strongest association seems to be with colon cancer, so those cells might be particularly sensitive. Breast cancer has a strong association, whereas some other cancers we don't see much of an association, like rectal cancer, prostate cancer, and stuff as well." (said at 1:04:24)

Epidemiological evidence consistently demonstrates that physical activity has the strongest and most convincing inverse associations with colon and breast cancer risks (along with endometrial cancer). In contrast, evidence for a protective association with prostate cancer is weak or null (sometimes showing slight positive associations due to screening detection bias), and historically, physical activity shows substantially weaker, inconsistent, or null associations with rectal cancer compared to colon cancer.

1:06:17supportedhighThe Science of Exercise for Cancer | Kerry Courneya, PhD

Weight training interventions in prostate cancer patients undergoing androgen deprivation therapy significantly improve muscle mass, muscular strength, fatigue, and energy.

"So these guys who are on these androgen deprivation therapies, we've done multiple studies with weight training, and that seems to be a really effective intervention for these guys to regain their strength, regain their muscle, and improvements in things like fatigue and energy." (said at 1:06:17)

Multiple systematic reviews and meta-analyses of randomized controlled trials demonstrate that resistance training (weight training), alone or combined with aerobic exercise, is an effective intervention for men with prostate cancer undergoing androgen deprivation therapy (ADT). Resistance exercise significantly improves upper- and lower-body muscular strength, increases lean body mass (muscle mass), and alleviates cancer-related fatigue while improving quality of life.

1:08:10supportedvery lowThe Science of Exercise for Cancer | Kerry Courneya, PhD

Preclinical animal trials demonstrate that exercise as a monotherapy slows the growth and metastatic spread of implanted cancer tumors in mice.

"We can take these mice, we can inject small number of cancer cells or implant small cancer tumors, and we can randomly assign them to exercise versus no exercise, just like the drug researchers would do, drug versus not. And we can show in those studies that exercise by itself, independent of any other treatments, tends to slow the growth and spread of these cancers." (said at 1:08:10)

Preclinical animal models consistently demonstrate that exercise interventions (such as voluntary wheel running or moderate swimming) administered without co-treatments can significantly inhibit tumor growth and reduce metastatic spread in mice bearing implanted tumors. For instance, Pedersen et al. (2016) demonstrated that randomized voluntary wheel running reduced tumor incidence and growth by over 60% across multiple murine tumor models via natural killer (NK) cell mobilization. Similarly, preclinical models of transplanted hepatoma and lung cancer show that moderate exercise independently curbs primary tumor progression and metastatic dissemination. Because this evidence is derived exclusively from animal models, the certainty is rated very low for translation to clinical human outcomes.

1:10:20supportedmoderatetheir own paperThe Science of Exercise for Cancer | Kerry Courneya, PhD

High-intensity interval training in men with prostate cancer undergoing active surveillance lowers prostate-specific antigen (PSA) levels.

"In addition to improvements in fitness and function and the types of things you might expect, we also showed that this high-intensity exercise lowered prostate-specific antigen levels, PSA levels." (said at 1:10:20)

In the ERASE phase II randomized clinical trial of 52 men with localized prostate cancer undergoing active surveillance, 12 weeks of supervised high-intensity interval training (HIIT) significantly decreased prostate-specific antigen (PSA) levels compared with usual care (between-group difference -1.1 μg/L, 95% CI -2.1 to 0.0, P = .04), as well as PSA velocity (-1.3 μg/L/y, P = .04) and prostate cancer cell line growth.

1:10:55supportedmoderatetheir own paperThe Science of Exercise for Cancer | Kerry Courneya, PhD

In vitro exposure of prostate cancer cells to serum from men who underwent high-intensity interval training suppresses prostate cancer cell growth compared to serum from non-exercising controls.

"And then we also looked at these prostate cancer cells in a petri dish, just an in vitro model where we exposed those prostate cancer cells to the serum of the men who exercised or the serum of the men who didn't exercise. And we showed that exposing them to the serum in the men who exercised reduced the growth of those prostate cancer cells" (said at 1:10:55)

In the ERASE phase 2 randomized controlled trial (PMID 34410322), 52 men with localized prostate cancer undergoing active surveillance were randomized to 12 weeks of supervised high-intensity interval training (HIIT) or usual care. In vitro bioassays evaluating serum effects demonstrated that exposure of the LNCaP prostate cancer cell line to post-intervention serum from the HIIT group significantly reduced cell growth compared with serum from the usual care group (-0.13 optical density units; 95% CI, -0.25 to -0.02; P = .02). Similar in vitro growth inhibition of prostate cancer cells following exposure to exercise-conditioned human serum has also been observed in other clinical cohorts (PMID 35152272).

1:17:19supportedhighThe Science of Exercise for Cancer | Kerry Courneya, PhD

In 2022, the American Society of Clinical Oncology (ASCO) published guidelines recommending aerobic and resistance exercise for all cancer patients being treated with curative intent.

"In fact, um 2 years ago, so only in 2022, 2 years ago, the American Society of Clinical Oncology put out its first exercise guidelines. So this is cancer doctors. So it's one thing for exercise specialists to say, "Hey, cancer patients should exercise," but now we have the cancer doctors themselves, their professional organization, ASCO, the American Society of Clinical Oncology, says all cancer patients who are being treated with curative intent should be recommended aerobic and resistance exercise while they go through treatments." (said at 1:17:19)

In 2022, the American Society of Clinical Oncology (ASCO) published its clinical practice guideline on exercise, diet, and weight management during cancer treatment (Ligibel et al., Journal of Clinical Oncology). Based on an extensive review of randomized trials and systematic reviews, the panel explicitly recommended that oncology clinicians recommend regular aerobic and resistance exercise to adult cancer patients undergoing active treatment with curative intent.

1:21:15supportedmoderatetheir own paperThe Science of Exercise for Cancer | Kerry Courneya, PhD

Exercise interventions in prostate cancer active surveillance patients significantly reduce fear of cancer recurrence and fear of progression.

"So the impact we showed in this study of exercise helping them manage that fear of cancer progression or fear of cancer recurrence really important helping them get on with their daily lives to say, "I have to live my life with cancer in the background even though, um, you know, I have this psychological stress."" (said at 1:21:15)

A randomized controlled trial (the ERASE trial) evaluating 52 men with prostate cancer on active surveillance showed that a 12-week supervised high-intensity interval training (HIIT) intervention significantly improved prostate cancer-specific anxiety (adjusted mean difference -2.7, p=0.024) and the fear of progression subscale (p=0.013) compared to usual care.

1:24:20supportedmoderateThe Science of Exercise for Cancer | Kerry Courneya, PhD

Skeletal muscle mass and lean muscle mass are strongly associated with physical functioning and quality of life, and predict cancer recurrence and survival outcomes in cancer patients.

"You know, I think what we're seeing is this idea of lean muscle mass, skeletal muscle mass being extremely important for getting through these treatments, predicting recurrence, predicting survival, strong associations with physical functioning and quality of life." (said at 1:24:20)

A substantial body of observational evidence and meta-analyses demonstrates that skeletal muscle mass and lean mass are significantly associated with physical functioning, quality of life, treatment tolerance, cancer recurrence, and overall survival across multiple cancer types. For example, a meta-analysis of non-metastatic colorectal cancer patients found low skeletal muscle index significantly predicted both higher overall mortality and higher recurrence risk. Systematic reviews also confirm consistent associations between muscle wasting and impairments in physical function and health-related quality of life, although prognostic strength can vary across specific tumor types (such as breast cancer).

1:25:48supportedmoderateThe Science of Exercise for Cancer | Kerry Courneya, PhD

Cancer treatments, including cardiotoxic chemotherapy agents, increase patients' risks of developing secondary chronic conditions such as cardiovascular disease, osteoporosis, and diabetes.

"many of the treatments that cancer patients get increase the risk for cardiovascular disease—some of these drugs are cardiotoxic—increase the risk of osteoporosis, uh they increase the risk of diabetes." (said at 1:25:48)

Cancer therapies are well-documented to increase the risk of multiple long-term non-malignant chronic conditions. For example, androgen deprivation therapy (such as GnRH agonists) commonly causes osteoporosis and significantly elevates the risk of developing diabetes and cardiovascular disease, in addition to direct cardiotoxicities associated with various chemotherapy regimens.

1:27:21supportedhighThe Science of Exercise for Cancer | Kerry Courneya, PhD

While complementary interventions for cancer patients (such as art therapy, music therapy, acupuncture, and massage) improve symptoms and quality of life, clinical evidence has not shown that they improve cancer survival or reduce recurrence risk.

"so they're offered a lot of complementary therapies: art therapy, music therapy, acupuncture, massage therapy, psychological counseling, stress management, and these are all having benefits on symptoms, side effects, quality of life, just like exercise. But none of those other interventions have shown any benefits for survival, any benefits for the disease itself or risk of recurrence." (said at 1:27:21)

Major clinical practice guidelines and systematic reviews in integrative oncology (such as the Society for Integrative Oncology/ASCO guidelines) recommend complementary therapies including acupuncture, massage therapy, music therapy, and mind-body practices specifically for alleviating treatment-related side effects, anxiety, pain, and improving quality of life. In contrast, clinical trial evidence has not demonstrated that these supportive complementary modalities improve overall cancer survival, prevent recurrence, or exert direct antitumor effects.

1:29:37supportedmoderateThe Science of Exercise for Cancer | Kerry Courneya, PhD

Overall physical activity levels among post-treatment cancer survivors are roughly similar to physical activity levels in the general population.

"When we compare cancer survivors with the general population, it's not much of a difference overall in terms of the physical activity levels. They're similar between the general population and cancer survivors." (said at 1:29:37)

Population-based studies using national survey data (such as NHANES and KNHANES) indicate that physical activity levels and guideline adherence are broadly similar between cancer survivors and the general non-cancer population, with both groups demonstrating predominantly low levels of physical activity. In representative studies comparing long-term cancer survivors to matched general-population controls, overall physical exercise rates did not show statistically significant differences, and accelerometer-measured moderate-to-vigorous physical activity levels were comparable, although some analyses note slight increases in sedentary time or modestly lower odds of meeting aerobic activity guidelines among survivors.

1:33:40supportedmoderateThe Science of Exercise for Cancer | Kerry Courneya, PhD

A study found that breast cancer patients who exercised during chemotherapy had a lower risk of recurrence or dying from breast cancer eight years later.

"I remember a study we did where we showed that breast cancer patients who exercised during chemo had a lower risk of recurrence or dying from breast cancer eight years later." (said at 1:33:40)

In an 8-year follow-up of the randomized Supervised Trial of Aerobic versus Resistance Training (START) (Courneya et al., 2014), breast cancer patients randomized to exercise during chemotherapy showed a numerically lower risk of recurrence and disease events compared to standard care (8-year disease-free survival of 82.7% vs. 75.6%, hazard ratio 0.68; recurrence-free interval hazard ratio 0.58). Because the trial was originally powered for quality-of-life endpoints rather than survival, these exploratory differences did not achieve formal statistical significance, but they align with the speaker's summary of the study's findings.

1:34:25supportedhighThe Science of Exercise for Cancer | Kerry Courneya, PhD

A randomized controlled trial in metastatic breast cancer patients demonstrated that an exercise intervention was cost-effective.

"Very recent study in breast cancer patients with metastatic cancer, wonderful randomized controlled trial showing many of these benefits we talked about, also did the cost-effectiveness analysis and showed this is a very cost-effective intervention as well" (said at 1:34:25)

A cost-utility analysis conducted alongside the multinational PREFERABLE-EFFECT randomized controlled trial (N = 357) evaluated a 9-month supervised exercise program in patients with metastatic breast cancer compared to usual care. The intervention produced gains in quality-adjusted life-years (QALYs) and net overall cost savings due to reductions in healthcare utilization and productivity losses, yielding high probabilities of cost-effectiveness across standard willingness-to-pay thresholds.

1:38:20supportedmoderatetheir own paperThe Science of Exercise for Cancer | Kerry Courneya, PhD

A study in rectal cancer patients found that an exercise intervention exacerbated radiation-induced skin irritation and diarrhea.

"So in one of our studies in rectal cancer patients, it looks like the exercise intervention made skin irritation from radiation worse. Exercise making skin irritation worse, it looks like it made diarrhea worse in these patients." (said at 1:38:20)

A phase II randomized controlled trial (EXERT trial) by Morielli, Courneya, and colleagues evaluated exercise during and after neoadjuvant chemoradiation in rectal cancer patients (n = 36). The trial found that exercise exacerbated certain treatment-related side effects compared to usual care, including significant worsening of stool frequency during neoadjuvant chemoradiotherapy and worsening of diarrhea and embarrassment in the post-treatment period.

1:39:24supportedmoderateThe Science of Exercise for Cancer | Kerry Courneya, PhD

Individuals who regularly exercise have higher rates of skin cancer than non-exercisers due to increased sun exposure.

"patients who regularly exercise have higher rates of skin cancer than non-exercisers; it's to this exposure." (said at 1:39:24)

Large prospective cohort analyses and systematic reviews confirm that individuals engaging in high levels of leisure-time physical activity have a modest but statistically significant increased risk of cutaneous melanoma compared to inactive individuals (relative risk ~1.27). Epidemiologists attribute this elevated incidence primarily to confounding from increased ultraviolet (UV) radiation and outdoor sun exposure during physical activity.

1:40:43supportedhighThe Science of Exercise for Cancer | Kerry Courneya, PhD

Bone is one of the most common sites of cancer metastasis.

"So one of the most popular places for um for cancer to spread is to the bone, and these bones can become a bit more brittle, so the risk of fracture in patients with metastatic bone disease" (said at 1:40:43)

Bone is well established as one of the most frequent sites of distant cancer metastasis. Overall, it represents the third most common site of metastasis across all cancer types (following the lungs and liver) and is the most common metastatic site for primary cancers such as breast and prostate cancer. Metastatic involvement disrupts bone remodeling, weakens bone architecture, and markedly increases the risk of skeletal-related events, including pathological fractures.

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