Among breast cancer patients, both chemotherapy and tamoxifen independently reduced the risk of developing a second cancer in the other breast, according to a study published online December 25 in the Journal of the National Cancer Institute. The risk reduction persisted for at least 10 and 5 years, respectively.For breast cancer patients the risk of developing cancer in the other breast is two to six times greater than the breast cancer risk of the general public. Studies have shown that taking tamoxifen for five years reduces the risk of cancer in the opposite breast among women who have estrogen receptor-positive breast cancer, but the studies did not clarify how long the protective effect lasts.
