茶与咖啡都显示对消化道癌症具有作用：咖啡喝得多可降低肠癌的危险性，茶喝得多对直肠癌似有保护作用。最近有研究旨在评价这些饮料对结直肠腺瘤（良性肿瘤）的作用。结果并未显示饮茶或咖啡对发生腺癌的危险有何相关。不过结果的分析有一些限制，包括研究组具有至少有一脉瘤 Both tea and coffee have been shown to have an effect on digestive tract cancers: drinking coffee can reduce the risk of bowel cancer, and tea drinking can have a protective effect on rectal cancer. Recent studies have aimed to evaluate the effect of these beverages on colorectal adenomas (benign tumors). The results did not show any correlation between the risk of developing adenocarcinoma by drinking tea or coffee. However, there are some limitations in the analysis of the results, including that the study group has at least one tumor