Lifestyle factors and colorectal cancer risk (1): Systematic review and meta-analysis of associations with body mass index

D. J. Harriss, G. Atkinson, K. George, N. Tim Cable, T. Reilly, N. Haboubi, M. Zwahlen, M. Egger, A. G. Renehan

    Research output: Contribution to journalReview articlepeer-review

    115 Citations (Scopus)


    Objective: Excess body weight, defined by body mass index (BMI), may increase the risk of colorectal cancer. As a prerequisite to the determination of lifestyle attributable risks, we undertook a systematic review and meta-analysis of prospective observational studies to quantify colorectal cancer risk associated with increased BMI and explore for differences by gender, sub-site and study characteristics. Method: We searched MEDLINE and EMBASE (to December 2007), and other sources, selecting reports based on strict inclusion criteria. Random-effects meta-analyses and meta-regressions of study-specific incremental estimates were performed to determine the risk ratio (RR) and 95% confidence intervals (CIs) associated with a 5 kg/m2 increase in BMI. Results: We analysed 29 datasets from 28 articles, including 67361 incident cases. Higher BMI was associated with colon (RR 1.24, 95% CIs: 1.20-1.28) and rectal (1.09, 1.05-1.14) cancers in men, and with colon cancer (1.09, 1.04-1.12) in women. Associations were stronger in men than in women for colon (P <0.001) and rectal (P = 0.005) cancers. Associations were generally consistent across geographic populations. Study characteristics and adjustments accounted for only moderate variations of associations. Conclusions: Increasing BMI is associated with a modest increased risk of developing colon and rectal cancers, but this modest risk may translate to large attributable proportions in high-prevalence obese populations. Inter-gender differences point to potentially important mechanistic differences, which merit further research.

    Original languageEnglish
    Pages (from-to)547-563
    Number of pages17
    JournalColorectal Disease
    Issue number6
    Publication statusPublished - 1 Jul 2009


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