Association between Prediagnostic Weight Change and Colon Cancer Risk in a Prospective Cohort
Embargo until
Date
2015-04-26
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Johns Hopkins University
Abstract
Background and Objectives: Obesity is defined by World Health Organization (WHO) as a BMI value over 30 and is associated with an increased risk of colon cancer in many studies. Whether weight change during adulthood is related to risk of colon cancer is not clearly related to the risk of cancer. This study not only investigates the relationship between body size at different ages and colorectal cancer risks but also focuses on the effect of weight changes throughout the adult years as related to both gender and stage of life.
Design and analysis: A prospective cohort of 15,008 cancer-free people is followed up 1989 through 2007. Cox proportional hazard regression models adjusted for life style risk factors were used to calculate hazard ratios and 95% confidence intervals of incident colorectal/colon cancer. Age standardized incidence and age adjusted risk ratios are compared to address the association between different categorization of BMI and colorectal cancers. Stratification by stage of life and by gender is conducted to evaluate effect modification by these factors.
Results: People with higher BMI at baseline tend to have higher risk of colorectal cancer during almost 20 years of follow up The risk of colon cancer for people with moderate weight gain between age 21 and study baseline is 1.35(95% CI is 0.91 to 1.99) compared to people with constant or lower weight gains. If the weight change occurred between age 21 and age 65, the hazard ratio is 1.45 (95%CI is 0.93 to 2.25). Hazard ratio of weight gain between age 21 and study baseline for men and women is 1.23(95% CI is 0.63 to 2.41) and 1.16(95% CI is 0.65 to 2.07) respectively.
Conclusion: The data from this study suggest that high BMI and high weight gain might increase the risk of colon but not rectal cancer. The life stage during which weight change is evaluated may modify the effect of weight change on risk of colon cancer. There is no significant effect modification of gender on the effects of weight gain.
Description
Keywords
weight change, colon cancer