This meta-analysis, by Sun et al, published in the journal Carcinogenesis, looked at the results of 13 studies concerning the anticancer properties of green and black teas. The analysis indicated a lower risk for breast cancer with green tea consumption, and a mild increase in risk associated with black tea on late stage breast cancer, but follow-up studies are necessary.
In addition, this study, by Yang et al, published in the journal Cancer Epidemiology, Biomarkers, & Prevention, found that regular consumption of green tea was inversely associated with the risk of colorectal cancer (CRC), particularly among women who maintained such habit over time. The longer the duration of lifetime tea consumption, the lower was the risk of CRC. CRC risk also decreased as the amount of tea consumption increased.