Breast cancer is a disease in which cells in the breast multiply out of control. There are different types of breast cancer. The type of breast cancer depends on which cells in the breast become cancerous.
Breast cancer can start in different parts of the breast. The breasts are made up of three main parts: lobules, ducts, and connective tissue. The lobules are the glands that produce milk. The ducts are the tubes that carry milk to the nipple. Connective tissue (made up of fibrous and fatty tissue) surrounds and supports all parts of the breast. Most breast cancers start in the ducts or lobules.
Breast cancer can spread outside the breast through blood vessels and lymphatic vessels. When breast cancer spreads to other parts of the body, it is said to have metastasized.
Common types of breast cancer
The most common types of breast cancer are:
Infiltrating ductal carcinoma. Cancer cells start in the ducts and then move out of them and multiply in other breast tissues. These invasive cancer cells can also spread, or metastasize, to other parts of the body.
Infiltrating lobular carcinoma. Cancer cells start in the lobules and then spread from the lobules to nearby breast tissues. These invasive cancer cells can also spread to other parts of the body.
There are other less common types of breast cancer, such as Paget’s disease,external icon medullary breast cancer, mucinous breast cancer, and inflammatory breast cancer.external icon
Ductal carcinoma in situ is a breast disease that can lead to infiltrating breast cancer. The cancer cells are only in the layer that covers the ducts and have not spread to other tissues in the breast.