Prospective study of the relationship between coffee and tea with colorectal cancer risk: The PLCO Cancer Screening Trial

Background: Coffee and tea are commonly consumed and carry potential anticancer components that could reduce the risk of colorectal cancer; however, their relationships with colorectal cancer risk remain inconsistent. Methods: A prospective analysis was carried out to examine the relationships of coffee and tea intake with colorectal cancer risk in 57 398 men and women in the intervention arm of the National Cancer Institute-Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial, a national screening study that limits differential detection biases. Coffee and tea intakes were assessed by food frequency questionnaire. Results: Six hundred and eighty-one incident colorectal cancer cases were ascertained during a median follow-up of 11.4 years. Greater coffee intake was not associated with risk of colorectal cancer (relative risk (RR)=1.08, 95% confidence interval (CI)=0.79-1.48, P-trend=0.23). Stratifying by cancer site (P-heterogeneity=0.48) or stage (P-heterogeneity=0.83) did not alter the relationship. Associations remained unchanged in subsets of participants for either caffeinated or decaffeinated coffee or when stratifying by several colorectal cancer risk factors. Similarly, greater tea intake was not associated with colorectal cancer risk overall (RR=0.77, 95% CI=0.55-1.09, P-trend=0.17) or by cancer site (P-heterogeneity=0.14) or stage (P-heterogeneity=0.60). These associations were not modified by several colorectal cancer risk factors. Conclusion: The findings of this study do not provide evidence to suggest that drinking coffee or tea is beneficial in protecting against colorectal cancer.