As a cancerous breast tumor grows, cancer cells may break away and be carried to other parts of the body through the bloodstream or lymphatic system. During this process, known as metastasis, the cancer cells can grow and develop in new locations in the body.
One of the first places breast cancer usually spreads is to the regional lymph nodes located under the arm, in the neck, under the chest bone, or just above the collarbone.
Breast cancer can also spread farther away from the breast to other parts of the body, such as the bones, lungs, and liver. Less often, breast cancer may spread to the brain. Breast cancer that has spread to a distant location in the body is referred to as stage IV or metastatic breast cancer.
However, even if the cancer has spread, it is still named for the area where it began. For example, if breast cancer spreads to the lungs, it is called metastatic breast cancer, not lung cancer. No matter whether the cancer has spread or how far it has spread, breast cancer can be treated and/or managed.
Breast Cancer Genetics
Although most women who develop breast cancer have no known risk factors and no family history of breast cancer, about 5% to 10% of breast cancers occur when gene changes, called mutations, are passed down in a family from one generation to the next.
Breast cancer may run in a family if other close relatives have been diagnosed with breast, ovarian, or other cancers, especially before age 50. If first-degree relatives developed breast cancer, the risk is 5 times the average risk.
There are several genes linked to an increased risk of breast cancer, but 2 of the most common are breast cancer genes 1 and 2. These are commonly shortened to BRCA1 or BRCA2. A mutation in either of these genes gives a woman an increased risk of developing breast and/or ovarian cancer, as well as other types of cancer.
Men who inherit these gene mutations also have an increased risk of developing breast cancer, as well as prostate cancer.
