Breast cancer is a cancer, which develops in breast tissues. It affects ducts carrying milk and glands making milk. Gland making milk is known as lobules. It may occur in both men and women but it is more common in women and is rare in men. Breast cancer can affect different tissues of the breast. It can affect ducts or tube moving milk from the breast to the nipple or milk producing parts lobules. It may be invasive or spreading from the milk duct or lobule to other tissues in the breast. It may also be non-invasive or confined to a smaller part of breast or in situ. Breast cancer in situ may affect the lining of the milk ducts or lobules and not invade nearby tissues. It may progress to invasive cancer.
Many patients may suffer from estrogen sensitive breast cancer. These types of breast cancer have receptors for estrogen on the surface of their cells. They are also known as estrogen receptor-positive cancer or ER-positive cancer. Some breast cancers may HER2-positive. HER2 is a gene helping cells growth, division or repair. This type of breast cancer quickly spreads and is more likely to be recurring.