Carcinoma in contralateral breast [Ref. KDT 6/e p. 304; Goodman & 10/e p. 1440,14411 Tamoxifen is associated with reduced risk of cancer in the contra- lateral breast. - It helps in preventing the recurrence and also helps to prevent the development of new cancers in the other breast. When used as an adjuvant chemotherapy it is usually taken for 5 years. When taken for 5 years it reduces the chance of original breast cancer coming back in the same breast or elsewhere. It also reduces the risk of developing secondary primary cancer. Tamoxifen may lead to endometrial hyperplasia and endometrial cancer -Tamoxifen is an SERM i.e. it has selective action on estrogen receptors. It will stimulate estrogen receptors in some organs while it will antagonize the estrogen receptors in other organs. - While tamoxifen blocks estrogen receptors on the breast, it stimulates these receptors in the uterus (because tamoxifen is a paial against of ER) Stimulation of estrogen receptors in the uterus may predispose the patients to endometrial hyperplasia and for endometrial cancer. Tamoxifen usage may lead to cataracts (occasional) 'Tamoxifen causes retinal deposites, decreased visual acuity and cataracts in occasional patients' - Goodman Gillman 117h/e p. 1557 Tamoxifen usage may lead to thromboembolism Tamoxffen increases the risk of thromboembolic events' - Goodman Gillman 1