MedGen

Breast cancer is a disease in which certain cells in the breast become abnormal and multiply uncontrollably to form a tumor. Although breast cancer is much more common in women, this form of cancer can also develop in men. In both women and men, the most common form of breast cancer begins in cells lining the milk ducts (ductal cancer). In women, cancer can also develop in the glands that produce milk (lobular cancer). Most men have little or no lobular tissue, so lobular cancer in men is very rare.

In its early stages, breast cancer usually does not cause pain and may exhibit no noticeable symptoms. As the cancer progresses, signs and symptoms can include a lump or thickening in or near the breast; a change in the size or shape of the breast; nipple discharge, tenderness, or retraction (turning inward); and skin irritation, dimpling, redness, or scaliness. However, these changes can occur as part of many different conditions. Having one or more of these symptoms does not mean that a person definitely has breast cancer.

A small percentage of all breast cancers cluster in families. These cancers are described as hereditary and are associated with inherited gene mutations. Hereditary breast cancers tend to develop earlier in life than noninherited (sporadic) cases, and new (primary) tumors are more likely to develop in both breasts.

In some cases, cancerous cells can invade surrounding breast tissue. In these cases, the condition is known as invasive breast cancer. Sometimes, tumors spread to other parts of the body. If breast cancer spreads, cancerous cells most often appear in the bones, liver, lungs, or brain. Tumors that begin at one site and then spread to other areas of the body are called metastatic cancers. [from MedlinePlus Genetics]

The presence of a carcinoma of the breast. [from HPO]

A tumor (abnormal growth of tissue) of the breast. [from HPO]

Any deviation from the normal structure or function of the skin or subcutaneous tissue that is manifested by a characteristic set of symptoms and signs. [from NCI]

A non-neoplastic or neoplastic disorder that affects the breast. Representative examples of non-neoplastic disorders include fibrocystic disease, gynecomastia, and mastitis. Representative examples of neoplastic disorders include fibroadenoma, lobular neoplasia, carcinoma, lymphoma, and sarcoma. [from NCI]

A header term that includes the following breast carcinoma subtypes determined by gene expression profiling: luminal A breast carcinoma, luminal B breast carcinoma, HER2 positive breast carcinoma, basal-like breast carcinoma, triple-negative breast carcinoma, and normal breast-like subtype of breast carcinoma. [from NCI]