Tamoxifen 20 mg Sandoz 100 tab. It is a drug used in the treatment of breast cancer. It belongs to a group of drugs called selective estrogen receptor modulators (SERMS). This drug blocks the action of estrogen in breast tissues, which helps slow down the growth and spread of cancer cells. Tamoxifen 20 mg Sandoz is available in tablet form and should be taken as prescribed by a doctor. It is an effective and widely used drug for the treatment of breast cancer, and has been proven to help improve patient survival rates.