Types of Breast Cancer

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.

Determining Your Type of Breast Cancer

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:

• In situ, meaning your cancer has not spread into your surrounding breast tissue
• Invasive or infiltrating, meaning your cancer has spread into surrounding tissue

Common Breast Cancer Types

Carcinomas are the most common type of breast cancer. These are named according to where they start and how they have spread.

In Situ Carcinomas

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 Carcinomas

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.

Less Common Breast Cancer Types

Other, less common, breast cancer types include:

• Inflammatory breast cancer, an invasive cancer occurring in about one to five percent of breast cancer cases
• Paget disease of the nipple, a cancer starting in the breast ducts then spreading to the nipple and areola in about one to three percent of all breast cancer cases
• Phyllodes tumors, mostly benign and rare breast tumors developing in the breast connective tissue
• Angiosarcoma, breast cancer starting in cells of blood vessels or lymph vessels and then involving breast tissue or skin in under one percent of all breast cancer cases