Biology of breast cancer and its clinical implications

Several established prognostic factors are used routinely in the clinical management of breast cancer. These factors include extent of axillary lymph node involvement, tumor size, histologic differentiation, and estrogen and progesterone receptor status. Unfortunately, these factors are not perfect predictors of outcome for the individual patient. This review highlights recent advances in the field of breast cancer biology that may ultimately improve our ability to predict prognosis more accurately, select therapy more appropriately, and possibly identify women who are at high risk for breast cancer development. In particular, studies addressing mechanisms of estrogen and antiestrogen resistance, clinical utility of flow cytometry, roles of certain oncogenes and tumor suppressor genes in breast cancer growth, and biologic factors involved in invasion and metastases are reviewed.