Therapeutic potential of tyrosine kinase inhibitors in breast cancer

Despite recent advances in the treatment of breast cancer, survival rates for patients with metastatic breast cancer remain poor, and hew treatments are still required for both hormone-dependent and hormone-independent disease. The epidermal growth factor receptor (EGFR) is a promising new target for anticancer therapy because it is commonly highly expressed in breast cancer and is implicated in the control of many aspects of tumor biology. Because expression of EGFR is inversely related to expression of the estrogen receptor (ER) and is associated with resistance to currently available breast cancer therapies, EGFR-targeted therapies may be valuable in the treatment of ER-negative tumors and endocrine-resistant, ER-positive tumors. Furthermore, the novel mechanism of action of EGFR-targeted therapies may complement the antitumor activity of existing treatment with cytotoxic agents, radiotherapy, or hormones. In this article, the small-molecule inhibitors of the tyrosine kinase activity of EGFR are discussed, with particular emphasis on the potential use of such agents at each stage of breast cancer, including a potential role in chemoprevention.