Breast cancer drug Washington - Agencies The breast cancer drug Tamoxifen may reduce some of the side effects caused by hormone therapy for prostate cancer, according to a new study. Androgen-suppression therapy is often used to slow the progression of advanced prostate cancer. But these drugs, which block testosterone activity, can cause side effects such as breast enlargement and pain that may stop men from using this treatment. German researchers examined the results of four independent clinical trials that examined the use of Tamoxifen to manage these side effects in prostate cancer patients undergoing androgen-suppression therapy. The study found that Tamoxifen reduced the risk of breast enlargement and breast pain in men at three, six, nine and 12 months of treatment compared to men who did not take Tamoxifen. Overall, Tamoxifen was more successful in reducing breast symptoms than radiation therapy or treatment with the aromatase inhibitor Anastrozole, which is also used to treat breast cancer. Few of the men treated with Tamoxifen stopped taking their medication during their year of treatment. Tamoxifen caused no significant side effects, according to the researchers.