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

Colorectal Dis. 2009 Jul;11(6):547-63. doi: 10.1111/j.1463-1318.2009.01766.x. Epub 2009 Jan 17.

Abstract

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/m(2) increase in BMI.

Results: We analysed 29 datasets from 28 articles, including 67,361 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.

Conclusion: 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.

Publication types

  • Meta-Analysis
  • Research Support, Non-U.S. Gov't
  • Review
  • Systematic Review

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Aged, 80 and over
  • Body Mass Index*
  • Colonic Neoplasms*
  • Female
  • Humans
  • Life Style
  • Male
  • Middle Aged
  • Obesity / complications*
  • Odds Ratio
  • Risk Factors
  • Sex Factors
  • Young Adult