The New Anti-Estrogens with Anti-Cancer Properties for Breast Cancer

Purpose: Considering the high prevalence of breast cancer and the radiation sensitivity of breast tissue, it is necessary to optimize the treatment process of this tumor, especially when using radiation therapy methods. The present study was conducted to investigate the effect and complications of new anti-estrogens on the effectiveness of breast cancer treatment. Materials and Methods: Articles were searched in PubMed, Science direct, Embassy, Cochran, and Scopus databases using the keywords Cancer AND Anti-estrogen, Breast Cancer AND anti-estrogen AND mice, Breast cancer And anti-estrogen AND rat. The authors reviewed the abstract and full text of the articles and the relevant studies were selected for systematic review. Results: The anti-estrogens used in the reviewed studies included TAM, RAL, SS1020, SS1010, GW5638, OSP, 4-OHTAM, and TOR. Anti-estrogen-related side effects included liver and uterine complications, especially in the case of using TAM anti-estrogen (54%). Moreover, uterine hypertrophy was observed using GW5638, RAL, and SS1010 anti-estrogens; while it happened with a lower percentage than TAM, 16%, 14%, and 13%, respectively. Side effects were significantly reduced by reducing the prescribed dose. So that this reduction for TAM is from 54% to 33%. In relation to the effect of antiestrogens on tumor treatment, the most effective and least complications were related to the antiestrogen "SS1020". Conclusion: Based on the results of reviewed studies, SS1020, which has no estrogenic and genotoxic activity, was safe and the most effective anti-estrogen against breast cancer in animals and also in humans.