<s>[INST] context: Hormonal drug therapy for breast cancer targets estrogen receptor-positive breast cancer. It aims at blocking the action of estrogen on estrogen receptor-positive breast cells. The hormonal therapy of choice for breast cancer in premenopausal women is Tamoxifen. Tamoxifen belongs to a class of drugs known as Selective Estrogen Receptor Modulator". Tamoxifen binds to the estrogen receptors on tumours and blocks the effect of estrogen on these cells. Tamoxifen is only effective in treating estrogen receptor-positive breast cancers. Therefore the tumour's hormone receptor status should be determined before deciding on a treatment option for breast cancer. Tamoxifen is used to treat patients with early sta2e breast cancer as well as those with metastatic breast cancer Adjuvant therapy with Tamoxifen Chemotherapy after primary t/t to increase the chance of cure. It helps in preventing the recurrence and also helps to prevent the development of new cancers in the other breast When used as adjuvant chemotherapy it is usually taken for 5 years. When taken for 5 years if reduces the chance of the original breast cancer coming back in the same breast or elsewhere. It also reduces the risk of developing secondary primary cancer. Metastatic cancer therapy with Tamoxifen As a treatment for metastatic breast cancer, the drug slows or stops the growth of cancer cells that are present in the body. Patient with metastatic breast cancer may have to take tamoxifen for varying lengths of time. ref - srb's manual of surgery 5e p530,551 [/INST] question: A drug used in estrogen-dependent breast cancer | options: A: Clomiphene citrate B: Tamoxifen C: Estrogen D: Adriamycin | answer: B </s>