Breast cancer accounts for 7% of all deaths from cancer and 15% of female deaths from cancer. It is the second most common cause of cancer death among women in the UK. Breast cancer most commonly presents as a lump in the breast, but the use of screening has also allowed very early cancers to be diagnosed before they can be detected clinically. The management of breast cancer has changed significantly over the past 50 years. Standard surgery used to be radical mastectomy and axillary node clearance, whereas today, patients are usually treated with breast-conserving techniques: wide local excision and sentinel lymph node biopsy followed by radiotherapy. The past few decades have also seen the development and wider use of systemic therapies: hormonal treatments, chemotherapy and targeted therapies such as trastuzumab. The mortality from breast cancer has steadily decreased over the last 20 years.
The female breast extends from the second to the sixth rib, and it is made up of 15–20 lobes which radiate out from the nipple. The nipple is surrounded by the areola. Each breast is divided into a central portion and four quadrants. The upper outer quadrant also contains the axillary tail. The lymphatic drainage from the breast is primarily to the axillary lymph nodes, but also to the internal mammary nodes, which lie in the thorax alongside the internal thoracic artery. A few lymphatic channels also communicate with those in the opposite breast and in the abdominal wall.
In the male and prepubertal female, the nipple and areola are small, and the breast tissue does not usually extend beyond the areola.
Types of tumour affecting the breast
Table 19.1 shows the range of tumours that can affect the breast. The most common are invasive ductal carcinoma and invasive lobular carcinoma. Invasive ductal carcinomas are positive for E-cadherin, whereas lobular carcinomas are negative for E-cadherin.
Incidence and epidemiology
Breast cancer is the most common malignancy in women in the UK and accounts for 30% of all new cancers in women. In 2011 there were 50,285 new cases of breast cancer in the UK, with 349 of these occurring in men.