Obesity and risk of colorectal cancer: a systematic review of prospective studies

PLoS One. 2013;8(1):e53916. doi: 10.1371/journal.pone.0053916. Epub 2013 Jan 17.


Background: Mounting evidence indicates that obesity may be associated with the risk of colorectal cancer (CRC). To conduct a systematic review of prospective studies assessing the association of obesity with the risk of CRC using meta-analysis.

Methodology/principal findings: Relevant studies were identified by a search of MEDLINE and EMBASE databases before January 2012, with no restrictions. We also reviewed reference lists from retrieved articles. We included prospective studies that reported relative risk (RR) estimates with 95% confidence intervals (CIs) for the association between general obesity [measured using body mass index (BMI)] or central obesity [measured using waist circumference (WC)] and the risk of colorectal, colon, or rectal cancer. Approximately 9, 000, 000 participants from several countries were included in this analysis. 41 studies on general obesity and 13 studies on central obesity were included in the meta-analysis. The pooled RRs of CRC for the obese vs. normal category of BMI were 1.334 (95% CI, 1.253-1.420), and the highest vs. lowest category of WC were 1.455 (95% CI, 1.327-1.596). There was heterogeneity among studies of BMI (P<0.001) but not among studies of WC (P=0.323).

Conclusions: Both of general and central obesity were positively associated with the risk of CRC in this meta-analysis.

Publication types

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

MeSH terms

  • Body Mass Index*
  • Colorectal Neoplasms / complications*
  • Humans
  • Obesity / complications*
  • Prospective Studies
  • Risk Assessment
  • Risk Factors
  • Waist Circumference*

Grant support

This work was financially sponsored by the Shanghai Rising-Star Program (No. 11QA1404800), the Grants from the National Natural Science Foundation of China (No. 81001069), and Shanghai Science and Technology Development Fund (No. 12140902300 and No. 12410707400). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.