Consumption of red meat and processed meat and cancer incidence: a systematic review and meta-analysis of prospective studies.
Level 2 - randomized trial
Systematic review and meta-analysis of prospective observational cohort studies
PubMed 34455534 · doi:10.1007/s10654-021-00741-9
What was done
A systematic review and random-effects meta-analysis of prospective cohort studies indexed in MEDLINE and EMBASE through December 2020. The authors assessed relative risks (RR) and 95% confidence intervals (CI) comparing highest versus lowest intake categories of unprocessed red meat, processed meat, and total red and processed meat for various cancer types across 148 published articles.
What was found
High unprocessed red meat intake was associated with greater risk of breast cancer (RR = 1.09, 95% CI 1.03–1.15), endometrial cancer (RR = 1.25, 95% CI 1.01–1.56), colorectal cancer (RR = 1.10, 95% CI 1.03–1.17; colon RR = 1.17, 95% CI 1.09–1.25; rectal RR = 1.22, 95% CI 1.01–1.46), lung cancer (RR = 1.26, 95% CI 1.09–1.44), and hepatocellular carcinoma (RR = 1.22, 95% CI 1.01–1.46). Processed meat consumption was significantly associated with higher risk of breast cancer (6% increase), colorectal cancer (18% increase; colon 21%, rectal 22%), and lung cancer (12% increase); exact confidence intervals were not reported in the abstract. Total red and processed meat consumption was significantly associated with colorectal cancer (RR = 1.17, 95% CI 1.08–1.26; colon RR = 1.21, 95% CI 1.09–1.34; rectal RR = 1.26, 95% CI 1.09–1.45), lung cancer (RR = 1.20, 95% CI 1.09–1.33), and renal cell cancer (RR = 1.19, 95% CI 1.04–1.37).
Why it matters
This study pools extensive prospective data showing consistent, modest statistical associations between red and processed meat intake and multiple cancer sites beyond the established colorectal link.
Limits
The analysis is restricted to observational studies, which cannot demonstrate causality and remain subject to residual confounding from lifestyle factors (e.g., smoking, obesity, diet quality) and dietary measurement error. The abstract lacks data on absolute risk, dose-response gradients, and confidence intervals for processed meat risk estimates.
Cited by
- supports Meat consumption has been implicated as a potential carcinogen, particularly for colorectal cancer.