Abstract 629: Coffee consumption and risk of colorectal cancer in the Cancer Prevention Study II Nutrition Cohort
Authors: Um Caroline Y. , McCullough Marjorie L. , Guinter Mark A. , Campbell Peter T. , Jacobs Eric J. , Gapstur Susan M. 
Published: August 2019

Abstract
Coffee consumption is inconsistently associated with colorectal cancer (CRC) risk, and further research on potential differences in associations by sex, colorectal subsite, smoking status, and caffeinated/decaffeinated coffee is needed. To investigate associations of coffee consumption with risk of CRC, we analyzed data from the Cancer Prevention Study-II Nutrition prospective cohort study. This analysis included 46,970 men and 60,007 women without a history of cancer at baseline. Those who completed a semiquantitative food frequency questionnaire in 1999 were followed through 2013, and 1,706 verified incident CRC cases were identified. Daily servings of caffeinated and decaffeinated coffee were comparable between men and women. Of the total population, 4.6% were current smokers, 46.1% were never smokers, and 47.3% were former smokers (2% missing smoking status). Cox proportional hazards regression models were used to calculate hazard ratios (HR) and 95% confidence intervals (CI) for the association of coffee consumption with CRC risk, adjusted for age, sex, body mass index, smoking, alcohol intake, total energy, total calcium (energy-adjusted), red and processed meat, and decaffeinated coffee in caffeinated coffee models and vice versa. For those who consumed 2 or more cups per day relative to those who consumed none or less than 1 cup per month, caffeinated coffee was not associated with CRC risk (HR 1.06, 95% CI 0.93-1.20), but decaffeinated coffee was associated with 15% lower risk of CRC (HR 0.85, 95% CI 0.73-0.99). Current smokers tend to consume more coffee in our study population and in other studies, and smoking is an established risk factor for some molecular sub-types of CRC; therefore, we repeated analyses stratified by smoking status (controlling for smoking duration for non-smokers and dose for current smokers). Among non-smokers (includes never and former smokers), the associations for coffee and CRC risk were similar to the overall results (HR 1.03, 95% CI 0.90-1.18 for caffeinated coffee; HR 0.87, 95% CI 0.74-1.02 for decaffeinated coffee). Among current smokers, the adjusted HRs and 95% CIs were 1.60 (0.80-3.22) for caffeinated coffee and 0.45 (0.19-1.03) for decaffeinated coffee. There was no evidence of effect modification by sex or colorectal subsite. Our results suggest that decaffeinated coffee may be associated with lower risk of CRC, but do not suggest potential differences in risk between men and women or by colorectal subsites. Further studies are needed to confirm these findings and to explore potential differences in caffeinated and decaffeinated coffee.
Citation Format: Caroline Y. Um, Marjorie L. McCullough, Mark A. Guinter, Peter T. Campbell, Eric J. Jacobs, Susan M. Gapstur. Coffee consumption and risk of colorectal cancer in the Cancer Prevention Study II Nutrition Cohort [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 629.