Many people do not know there are multiple types of breast cancer. The three most common breast cancers are ductal carcinoma in situ, invasive ductal carcinoma and invasive lobular carcinoma.
Your type of breast cancer depends on which cells in your breast show disease. The majority of breast cancers are carcinomas. These cancers are tumors starting in your epithelial cells, cells lining your organs and tissues.
If you do not have a carcinoma, your breast cancer is one of the less common types of breast cancers. These include sarcomas, Paget disease, phyllodes and angiosarcomas. These cancers start in muscle, fat or connective tissue cells.
One breast tumor can be multiple types of cancer. But not all breast cancers involve tumors or lumps. Some very rare breast cancers do not form these masses at all.
When you gain a breast cancer diagnosis, your pathologist will use a biopsy to determine the type of cancer. He or she will also determine whether the cancer has spread into other tissues around the tumor or mass.
Terms describing the extent of cancer include:
Carcinomas are the most common type of breast cancer. These are named according to where they start and how they have spread.
Ductal carcinoma in situ is a breast cancer not yet invading other tissues. Another name for this cancer is intraductal carcinoma.
Lobular carcinoma in situ is a non-cancerous breast change. In this breast disease sometimes called lobular neoplasia, the cells that look like cancer cells grow into the milk-producing gland lobules. But these cells do not grow through the lobule walls.
Invasive breast cancer is cancer that has spread into the breast tissue surrounding the original mass or tumor. The most common of the many invasive breast cancer types are invasive ductal carcinoma and invasive lobular carcinoma.
Other, less common, breast cancer types include: