title: A quantitative analysis of body mass index and colorectal cancer: findings from 56 observational studies.
abstract: 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 > or = 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.
authors.affiliation: Department of Nutrition, Harvard School of Public Health, Boston, MA 02115, USA. yining@hsph.harvard.edu
authors.forename: Y
authors.initials: Y
authors.lastname: Ning
authors.forename: L
authors.initials: L
authors.lastname: Wang
authors.forename: E L
authors.initials: EL
authors.lastname: Giovannucci
mesh_terms: D000367:Age Factors; D015992:Body Mass Index; D015179:Colorectal Neoplasms / Q000453:epidemiology* / Q000209:etiology; D005260:Female; D006801:Humans; D008297:Male; D009765:Obesity / Q000150:complications*; D050177:Overweight / Q000150:complications; D018570:Risk Assessment; D012307:Risk Factors; D012737:Sex Factors; D013851:Thinness