Body mass index category as a risk factor for colorectal adenomas: a systematic review and meta-analysis.
OBJECTIVE
The association between increasing body weight and colorectal adenoma prevalence has been suggested to follow a similar pattern to excess weight and colorectal cancer, although the magnitude of this relationship has not been validated. The objective of this study was to quantify the association and dose-response relationship between body mass index (BMI) and colorectal adenoma prevalence in clinical trials.


METHODS
We systematically reviewed 23 studies (168,201 participants), which compared the prevalence of colorectal adenomas according to World Health Organization BMI categories. We assessed the effects of each BMI category on colorectal adenomas where odds ratio (OR) was used as a surrogate for effect size, and applied multivariate meta-analysis as a method of sensitivity analysis to evaluate the robustness of our findings and to analyze adenoma prevalence by multiple BMI categories simultaneously to assess for a dose-response relationship. Heterogeneity and publication bias were assessed.


RESULTS
Subjects with a BMI of ≥25 had a significantly higher prevalence of colorectal adenomas (OR=1.24 (95% confidence interval (CI): 1.16-1.33), P<0.01) when compared with those with BMI<25. Multivariate meta-analysis also confirmed a positive association between higher BMI categories and the prevalence of colorectal adenoma (BMI: 25-30 vs. BMI<25; OR=1.21 (95% CI: 1.07-1.38), P<0.01; BMI≥30 vs. BMI<25; OR=1.32 (95% CI: 1.18-1.48), P<0.01) and revealed a dose-response relationship.


CONCLUSIONS
The positive association between obesity and colorectal adenoma prevalence demonstrates an underlying dose-response relationship according to BMI. Colorectal centers may benefit from the timely screening of obese patients for colorectal adenomas in addition to clarifying the biological role of adiposity on colorectal tumor initiation and progression.
Department of Surgery and Cancer, Imperial College London, UK.
Koji
K
Okabayashi
Hutan
H
Ashrafian
Hirotoshi
H
Hasegawa
Jae-Hoon
JH
Yoo
Vanash M
VM
Patel
Leanne
L
Harling
Simon P
SP
Rowland
Mariam
M
Ali
Yuko
Y
Kitagawa
Ara
A
Darzi
Thanos
T
Athanasiou
D000236:Adenoma / Q000209:etiology*; D015992:Body Mass Index; D015179:Colorectal Neoplasms / Q000209:etiology*; D006801:Humans; D009765:Obesity / Q000150:complications*; D012307:Risk Factors