Abstract B77: Short-term weight change and colon and rectal cancer risk in the EPIC cohort
Authors: Bisschop Charlotte Noelle Steins , Gils Carla H. van , Emaus Marleen J. , Mesquita Bas Bueno de , Aleksandrova Krasimira , Boeing Heiner , Jenab Mazda , Riboli Elio , Norat Teresa , Peeters Petra H.M. , May Anne M. 
Published: January 2014

Abstract
Background: BMI (Body Mass Index) has been considered as a risk factor for colon cancer but not for rectal cancer. Less is known about the association between weight change and colon and rectal cancer risk. In this study we investigated how risk for colon and rectal cancer develops for weight change within the follow-up period of the European Prospective Investigation into Cancer and nutrition (EPIC) cohort.
Methods: We investigated the relationship between weight change and subsequent colon and rectal cancer risk among 328.781 participants aged between 25 and 70 years from the EPIC cohort. EPIC is a large ongoing European study in 23 centres in 10 European countries. At recruitment (1992-2000), weight, height and waist circumference were measured and detailed dietary and lifestyle data were collected through questionnaires. Body weight was reassessed on average 5 years after recruitment (range 0.3 - 13 years) and was mainly self-reported. In the subsequent years, participants were followed for the occurrence of cancer for up to 13 years.
We used Cox regression analysis, with age as the time variable, and stratified the models according to study center and age, with further adjustment for body mass index (BMI) and waist circumference at recruitment, smoking status and intensity, physical activity, educational level, alcohol intake and intake of fibres, vegetables, fruits, fish and meat. In women we additionally adjusted for menopausal status, use of oral contraceptives and use of hormone replacement therapy. Weight change (kg/year) was defined as sex specific quintiles, with the combined quintiles 2 and 3 as the reference category defined as those with stable weight (i.e. weight change of -2.9 to 1.4 kg per 5 years in men; and -1.9 to 1.9 kg per 5 years in women).
Results: During 2.1 million person-years (mean duration of follow-up 6.4 years) after the second assessment of weight, 480 and 781 incident colon cancer and 354 and 393 rectal cancer cases were identified in men and women, respectively. Moderate weight gain was associated with an increased risk of colon cancer in men (weight gain of 1.4 -3.8kg/ 5 years; 4th quintile, HR 1.32; 95% CI 1.03; 1.69) and women (weight gain of 1.9-4.2 kg/ 5 years; 4th quintile, HR 1.29; 95% CI 0.99; 1.68). No effects were found for higher weight gain, or for the relationship between weight gain and rectal cancer risk in both men and women. There was no interaction between weight change and BMI, waist circumference or hormone replacement therapy.
Conclusion: Our preliminary results indicate that the risk on colon cancer is increased in men and women with moderate short term weight gain, but not in those with high weight gain. The latter might be due to competing risks in men with high weight gain. This finding needs further investigation and will be discussed at the conference in more detail.
Citation Format: Charlotte Noelle Steins Bisschop, Carla H. van Gils, Marleen J. Emaus, Bas Bueno de Mesquita, Krasimira Aleksandrova, Heiner Boeing, Mazda Jenab, Elio Riboli, Teresa Norat, Petra H.M. Peeters, Anne M. May. Short-term weight change and colon and rectal cancer risk in the EPIC cohort. [abstract]. In: Proceedings of the Eleventh Annual AACR International Conference on Frontiers in Cancer Prevention Research; 2012 Oct 16-19; Anaheim, CA. Philadelphia (PA): AACR; Cancer Prev Res 2012;5(11 Suppl):Abstract nr B77.