Worldwide, breast cancer is the second most common type of cancer (10.4 % of all cancer incidence). Breast cancer is by far the most common cancer amongst women, with an incidence rate more than twice that of colorectal cancer and cervical cancer. Breast cancer is the fifth most common cause of cancer death. In 2004, breast cancer caused 519,000 deaths worldwide (7% of cancer deaths; almost 1% of all deaths).
Breast cancer is about 100 times as frequent among women as among men, but survival rates are equal in both sexes.
Currently, all breast cancers should be tested for expression, or detectable effect, of the estrogen receptor (ER), progesterone receptor (PR) and HER2/neu proteins.
HER2/neu (also known as ErbB-2) stands for "Human Epidermal Growth Factor Receptor 2" and is a protein giving higher aggressiveness in breast cancers. It is a member of the ErbB protein family. HER2/neu has also been designated as CD340 (cluster of differentiation 340) and p185.
HER2/neu is notable for its role in the pathogenesis of breast cancer and as a target of treatment. It is a cell membrane surface-bound receptor tyrosine kinase and is normally involved in the signal transduction pathways leading to cell growth and differentiation.
The HER2 gene is a proto-oncogene located at the long arm of human chromosome 17 (17q21-q22).
Approximately 15-20 % of breast cancers have an amplification of the HER2 gene or overexpression of its protein product.
Overexpression of this receptor in breast cancer is associated with increased disease recurrence and worse prognosis. HER2/neu also helps to determine the treatment strategies. Patients with overexpression of HER2 don't respond to hormonal (tamoxifen) therapy and some chemotherapy. Herceptin (Trastuzumab) therapy is effective and is recommended in breast cancer where the HER2/neu receptor is overexpressed.
Overexpression also occurs in other cancer such as ovarian cancer, stomach cancer, and biologically aggressive forms of uterine cancer, such as uterine serous endometrial carcinoma.
HER2/neu, ER and PR are routinely done in Saridar Lab.