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A quantitative analysis of body mass index and colorectal cancer: findings from 56 observational studies

Authors

  • Y. Ning,

    Corresponding author
    1. Department of Nutrition, Harvard School of Public Health, Boston, MA, USA;
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  • L. Wang,

    1. Department of Nutrition, Harvard School of Public Health, Boston, MA, USA;
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  • E. L. Giovannucci

    1. Department of Nutrition, Harvard School of Public Health, Boston, MA, USA;
    2. Channing Laboratory, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA;
    3. Department of Epidemiology, Harvard School of Public Health, Boston, MA, USA
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  • The work was supported by grants R01 CA55076 from the National Cancer Institute. Support for Dr. Ning was provided by James K. Knox Memorial Fund, Department of Nutrition, Harvard School of Public Health.

Y Ning, Department of Nutrition, Harvard School of Public Health and Channing laboratory, 677 Huntington Avenue, Boston 02115, MA, USA. E-mail: yining@hsph.harvard.edu

Summary

To perform a systematic review of studies reporting on the association between body mass index (BMI) and the risk of colorectal cancer, we conducted a meta-analysis and meta-regression analysis. The identified 56 studies were conducted among 7 213 335 individuals including 93 812 cases. Compared with BMI <  23.0 kg m−2, BMI of 23.0–24.9, 25.0–27.4, 27.5–29.9 and ≥30.0 kg m−2 were associated with 14%, 19%, 24% and 41% increased risks, respectively. Asians and premenopausal women had sharply increased risk from BMI < 23 kg m−2 to general ‘normal’ range (23–25 kg m−2). Each 5 kg m−2 increment was associated with 18% increased risk. Meta-regression analysis indicated that the association was stronger for colon than rectal cancer (P < 0.001), for men than women (P < 0.001), for self-reported BMI than directly measured BMI (P < 0.001), and for studies adjusting for physical activity than not adjusting (P < 0.001). The variation of the reported risk estimates for the association can be partly explained by cancer site, sex, women menopausal status, BMI assessment and adjustment of confounding variables.

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