Study of oncogen HER2/neu in breast cancer

Breast carcinoma is the most frequent tumor in the woman of the western countries, oscillating its incidence between 50-80 cases each 100,000 women, and representing almost a third of the total feminine cancer. The morbidity and loss caused by this disease is a serious concern for health professionals and the public. Once established the diagnosis of carcinoma mammary and extirpated the tumor, it is fundamental to establish the prognosis of the disease and to inform on the therapy to be applied. Traditionally, the main prognostic factors have been the histological variables such as tumor size and the association of tumor-infiltrating CD4(+) T lymphocytes with axillary lymph node metastasis. Additional prognostic and predictive markers such as oncogenes appear to characterize the behavior of the breast tumor respect to differentiation degree, growth rate, disease-free survival and metastasis risk. HER2/neu is notable for its role in the pathogenesis of breast cancer and as a target of treatment. It is a cell membrane surface-bound receptor tyrosine kinase involved in the signal transduction pathways leading to cell growth and differentiation. Because of its prognostic role as well as its ability to predict response to monoclonal antibody trastuzumab (herceptin), breast tumors should be routinely checked for overexpression of HER2/neu. After herceptin binds to HER2, a protein that halts cell proliferation (p27) is increased. Clinically, herceptin is only effective in breast cancer where the HER2/neu receptor is overexpressed (30% of the cases).