Breast cancer: Molecular basis and therapeutic strategies (Review)

Breast cancer is the most common malignancy among women. It is frequently treated with chemotherapy and hormone therapy. More recently, however, 'targeted therapy' has emerged as an important approach to cancer therapy. Targeted therapy works by interfering with a specific molecular target, though inter-individual variability in drug response often causes treatment failure. Anticancer agents inhibit breast cancer progression by several different mechanisms. The Ras/Raf/MEK/ERK signal transduction pathway regulates cell cycle progression and apoptosis in diverse cell types. Alterations in this pathway are often associated with human cancer, including breast cancer. Understanding breast cancer biology is useful for the identification of appropriate anticancer drugs. This review describes the effect of gene alterations on breast cancer development. In addition, it shows how each anticancer drug used to treat breast cancer may block aberrant cell proliferation. Finally, the mechanisms of resistance to therapy are also discussed.