[Additional effect of SERM: mammary gland].

One of selective estrogen receptor modulators (SERMs), tamoxifen, has been widely used for prevention of breast cancer, postoperative adjuvant therapy and treatment of advanced breast cancer. The relation of a long-term administration of tamoxifen and its adverse effects have been extensively investigated. Favorable effects of tamoxifen are:the reduction in the risk of contralateral breast cancer, gain in bone density in postmenopausal women and decrease in serum low-density lipoprotein cholesterol. Unfavorable effects are: gynecologic problems and the increase in the risk of endometrial cancer and thromboembolism. In contrast, another SERM, raloxifene, has reported to have similar favorable adverse effects but no unfavorable effect on endometrium.