Tea consumption and the risk of colorectal cancer in Sweden

The association between tea drinking and colorectal cancer risk remains unclear. The evidence for black tea is sparse but may indicate an increased risk with regular use. Because black tea is a common beverage in many populations, the significant twofold increased risk of colon cancer recently reported from a large prospective cohort of male Finnish smokers is disconcerting. Using Cox proportional hazards models to estimate relative risks, we examined this association in a large, population-based prospective cohort study in Sweden. During an average 9.6 years of follow-up of our cohort of 61,463 women (588,270 person yr), we observed 460 incident cases of colorectal cancer (291 colon, 159 rectal, and 10 with both colon and rectal cancer). We observed no association between tea consumption and combined colorectal cancers in age- or multivariate-adjusted models. With the use of collapsed exposure categories, the multivariate-adjusted relative risk for the highest exposure (greater than or equal to2 cups/day) compared with the lowest (never or seldom) was 0.97 (95% confidence interval = 0.63-1.48, p for trend = 0.34). Examining the association by cancer subsite, we observed no association between tea consumption and proximal, distal, or combined colon cancers. We did, however, observe a nonsignificant positive association with rectal cancers, which became stronger and statistically significant among women greater than or equal to 65 years of age at baseline. Our data do not support the strong, dose-dependent positive association with colon cancer found in the Finnish study.