[RESUMEN] ABSTRACT

Breast cancer is one of the principal causes of death in women. Chemotherapy is one of the effective treatments used in breast cancer patients. However, in several cases chemotherapy fails because tumor cells may develop several mechanisms of antitumor drug resistance. There are different genes/proteins that, when abnormally expressed in the tumors, prevent the function of the antitumor drugs. Among the proteins related with chemotherapy resistance is the proteins P170, HER-2/neu, and heat shock. Our research group is studying molecules expressed in breast tumors that can be associated with sensitivity/resistance to chemotherapy. The objective is to help oncologists in the selection of the more effective chemotherapies to individual breast cancer patients.