GREEN TEA CONSUMPTION AND PROSTATE CANCER RISK IN JAPANESE MEN: A PROSPECTIVE STUDY

摘要

I read with great interest the recent Journal article by Kurahashi et al. (1) linking green tea with prostate cancer prevention in Japanese males. Recent studies indicate that green tea (Camellia sinensis) may also have a major role to play in the chemoprevention of other systemic malignancies.For instance, polyphenols found in green tea have been shown to prevent the formation of aberrant crypt foci in the colon, which are precursors of colorectal cancer (2). Yang et al. (3), in a recent study conducted among Chinese women, reported that the relative risk of colorectal cancer was 0.63 for women who drank green tea regularly in comparison to women who did not drink green tea regularly. Thus, green tea intake can significantly decrease the risk of colorectal cancer. Polyphenols found in green tea have also been shown to be potent inhibitors of the carcinogenic effects of ultraviolet light on the skin (4). Studies indicate that green tea can very effectively inhibit the formation of mixed cutaneous tumors as well as cutaneous squamous cell carcinomas. Qin et al. (5), in a recent study, have also shown that epigallocatechin-3-gallate found in green tea enhances apoptosis in bladder cancer cells (5). Epigallocatechin-3-gallate also inhibits the expression of amyloid precursor protein and thus decreases the risk of oral squamous cell carcinomas (6). Zhang et al. (7), in another recent study, have reported that green tea consumption is associated with a significant decline in the risk of breast cancer. In their study, the authors reported that the odds ratio for developing breast cancer in women who drank 500-749 g of green tea a year was 0.59.