RESUMEN
Breast cancer is the second largest disease affecting women worldwide. It remains the most frequently reported and leading cause of death among women in both developed and developing countries. Tamoxifen and raloxifene are commonly used selective estrogen receptor modulators for treatment of breast cancer in women with high risk, although resistance occurs by tamoxifen after 5 years of therapy and both drugs cause uterine cancer and thromboembolic events. Aromatase inhibitors (AIs) are one of the optional modes used for breast cancer treatment. The combination of AIs along with tamoxifen can also be beneficial. Various therapeutic agents from different sources are being studied, which further need to be improved for potential outcome. For this, clinical trials based on large number of patients with optimal dose and lesser side effects have to be more in practice. Despite the clinical trials going on, there is need of better molecular models, which can identify high risk population, new agents with better benefit having less side effects, and improved biomarkers for treating breast cancer.
RESUMEN
Breast cancer is one of the most common cancers in women around the globe Tamoxifen is used for the last 40 years as an endocrine therapy for breast cancer. This resulted in the reduction of mortality rate by 30% and it still remains one of the most effective therapies against breast cancer. However, resistance against tamoxifen is still one of the major hurdles in the effective management of breast cancer. Intense research has been conducted in the past decade to further explore its resistance mechanism, but still a lot of research will be needed to effectively alleviate this problem. Several biochemical factors and molecular pathways, such as the modulation of ER signaling, upregulation of growth factors had been observed as key factors for tamoxifen resistance (TR). After, initial therapy of five to ten years, breast cancer patients develops resistance towards this drug. The resistance leads to the development of other cancers like uterine cancer. Here, we briefly explore all the molecular events related to tamoxifen resistance and focus on its mechanism of action as well as other pharmacological approaches to better its beneficial effects in the treatment of breast carcinoma.