We have yet to see if the study is of publication quality and makes its way to some journal. I think I saw it mentioned somewhere in the telegraph article that it could be just survivors effect. "Men who are heavy tea drinkers are more likely to develop prostate cancer" might be just "Men who are heavy tea drinkers are more likely to (live longer to reach prostate cancer riskier age) to develop prostate cancer".
The risk of prostate cancer has been proved to be correlated to age, and jumps up rapidly with aging.
Anti-oxidants can shield cancer cells from chemo. Mostly from supplements including green tea extract. Discuss any supplements you take with your oncologist. In addition heavy consumption of tea or coffee can lead to malabsorption issues with iron and can make problems with anemia worse and anemia is a common problem with chemo.