Some types of breast cancer need estrogen to grow and divide. These types have receptors or sites to which estrogen attaches, promoting cancer growth. These are known as estrogen receptor positive cancers. Tamoxifen blocks the estrogen from binding to these receptors, preventing the breast cancer from growing. For women with estrogen receptor positive breast cancer, taking tamoxifen for 5 years significantly reduces the risk of recurrence of breast cancer and the risk of dying from breast cancer.
Tamoxifen is given in pill form.
The usual dosage is 20 mg a day. Women who are taking tamoxifen to prevent breast cancer, or those who have breast cancer that has not spread to other parts of the body usually take tamoxifen for 5 years. The side effects Most side effects from tamoxifen are tolerable and can be managed easily. Common side effects include hot flashes, vaginal dryness, vaginal discharge, and itching. These are similar to symptoms commonly experienced during menopause.