Subgroup effects in a randomised trial of different types and doses of exercise during breast cancer chemotherapy.
Level 2 - randomized trial
Moderator analysis of an individual randomized controlled trial
PubMed 25144625 · doi:10.1038/bjc.2014.466
What was done
In the Combined Aerobic and Resistance Exercise (CARE) Trial, 301 breast cancer patients initiating chemotherapy were randomized to three supervised exercise sessions per week of either: standard-dose aerobic exercise (25-30 min), higher-dose aerobic exercise (50-60 min), or higher-dose combined aerobic and resistance exercise (50-60 min). Authors evaluated baseline demographic, fitness, and cancer characteristics as potential moderators of treatment response on patient-reported symptoms and health-related fitness.
What was found
Body mass index significantly moderated intervention effects on bodily pain (P for interaction = 0.038), endocrine symptoms (P = 0.029), taxane/neuropathy symptoms (P = 0.013), aerobic fitness (P = 0.041), muscular strength (P = 0.007), and fat mass (P = 0.005), with healthy-weight patients benefiting more from higher-dose interventions than overweight/obese patients. Menopausal status, age, and baseline fitness also moderated patient-reported symptoms, with premenopausal, younger, and fitter patients deriving greater benefits from higher-dose exercise. Absolute effect sizes and confidence intervals were not reported in the abstract.
Why it matters
This study shows that exercise dose-response relationships during chemotherapy vary by patient characteristics, indicating that higher exercise volumes are especially effective in younger, fitter, and leaner patients.
Limits
The abstract provides interaction p-values but no point estimates, confidence intervals, or subgroup-specific sample sizes. As an exploratory moderator analysis, results carry risk of type I error from multiple testing and may be underpowered for smaller subgroups.
Cited by
- supports 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.