Red and processed meat and colorectal cancer incidence: meta-analysis of prospective studies.
Level 3 - non-randomized controlled study
Meta-analysis of prospective cohort (non-randomized) observational studies
PubMed 21674008 · doi:10.1371/journal.pone.0020456
What was done
A systematic search of PubMed up to March 2011 was conducted to identify prospective cohort studies evaluating red and processed meat intake and colorectal cancer incidence. Relative risks (RR) and 95% confidence intervals (CI) were extracted and pooled using random-effects models weighted by inverse variance for highest-versus-lowest intake comparisons, linear dose-response analyses, and non-linear dose-response modelling.
What was found
Combining red and processed meat intake showed an increased risk of colorectal cancer for highest versus lowest intake (RR 1.22, 95% CI 1.11–1.34) and for each 100 g/day increase (RR 1.14, 95% CI 1.04–1.24). Risk increased approximately linearly up to roughly 140 g/day, where the curve plateaued. Analyzed separately, colorectal cancer risk increased with fresh red meat (RR 1.17 per 100 g/day increase, 95% CI 1.05–1.31) and processed meat (RR 1.18 per 50 g/day increase, 95% CI 1.10–1.28). Similar patterns were observed for colon cancer, whereas separate analyses for rectal cancer showed no statistically significant association.
Why it matters
This review updates previous international benchmarks by quantifying a continuous, near-linear dose-response relationship between red/processed meat consumption and colorectal cancer risk up to 140 g/day.
Limits
The analysis relies entirely on observational cohort data, making it vulnerable to residual confounding from lifestyle and other dietary factors. The total number of pooled studies and participants is not stated in the abstract, and variations in dietary assessment methods or cooking/processing techniques are not specified.
Cited by
- supports The WHO analysis reported an 18% increased risk of colorectal cancer for every 50 grams of processed meat consumed daily, and a 17% increased risk per 100 grams of red meat.