Introduction

Breast cancer is the most common type of cancer and is the second leading cause of cancer mortality in women. It was estimated that 207, 090 women would be diagnosed with and 39, 840 women would die of cancer of the breast in 2010 in the USA. There is a rising incidence of breast cancer; however, on the brighter side, there has been a decline in mortality over the last several years (1). These changes are attributed to both early diagnosis and more effective treatment. Risk factors for breast cancer include age, family history and genetics, a later first pregnancy, and obesity.

Infiltrating or invasive ductal cancer is the most common histological type of breast cancer and comprises 70–80% of all cases. Other types of breast cancer include DCIS (ductal carcinoma in situ), LCIS (lobular carcinoma in situ), and inflammatory and invasive lobular carcinoma. Tumors involving the nipple are classified as Paget's disease (intraductal and invasive ductal).

Initial disease staging is a crucial step in optimizing the management of breast cancer patients. Increasingly, molecular phenotyping of breast cancer is applied to help ascertain whether the cancer is likely to respond to chemotherapy or immunotherapy. A variety of factors influence the choice of treatment options including but not limited to age, menopausal status, local disease status (e.g., size and extent of the mass), axillary nodal disease involvement, hormone receptor status (estrogen/progesterone receptor expression), and Human Epidermal Growth Factor Receptor 2 (HER2/neu) expression.