Types of Breast Cancer
There are two main types of breast cancer:
- Ductal carcinoma starts in the tubes (ducts) that move milk from the breast to the nipple. Most breast cancers are of this type.
- Lobular carcinoma starts in parts of the breast, called lobules, that produce milk.
Other types of breast cancer include:
- Invasive (or Infiltrating) Ductal Carcinoma (IDC)
- Invasive (or Infiltrating) Lobular Carcinoma (ILC)
There are several types of breast cancer, although some of them are quite rare. It is not unusual for a single breast tumor to be a combination of these types and to have a mixture of invasive and in situ cancer.
Ductal carcinoma in situ (also known as intraductal carcinoma) is the most common type of non-invasive breast cancer. DCIS means that the cancer cells are inside the ducts but have not spread through the walls of the ducts into the surrounding breast tissue.
About 1 out of 5 new breast cancer cases will be DCIS. Nearly all women diagnosed at this early stage of breast cancer can be cured. A mammogram is often the best way to find DCIS early.
When DCIS is diagnosed, the pathologist (a doctor specializing in diagnosing disease from tissue samples) will look for an area of dead or dying cancer cells, called tumor necrosis, within the tissue sample. If necrosis is present, the tumor is likely to be more aggressive. The term comedocarcinoma is often used to describe DCIS with necrosis.
Although not a true cancer, LCIS (also called lobular neoplasia) is sometimes classified as a type of non-invasive breast cancer, and this is why it is included here. It begins in the milk-producing glands but does not grow through the wall of the lobules.
Most breast cancer specialists think that LCIS itself does not become an invasive cancer very often, but women with this condition do have a higher risk of developing an invasive breast cancer in the same breast or in the opposite breast. For this reason, women with LCIS should pay close attention to having regular mammograms.
This is the most common type of breast cancer. It starts in a milk passage (duct) of the breast, has broken through the wall of the duct, and invaded the fatty tissue of the breast. At this point, it may have the ability to spread (metastasize) to other parts of the body through the lymphatic system and bloodstream. About 8 out of 10 invasive breast cancers are infiltrating ductal carcinomas.
Invasive lobular carcinoma starts in the milk-producing glands (lobules). Like IDC, it can spread (metastasize) to other parts of the body. About 1 out of 10 invasive breast cancers are ILCs. Invasive lobular carcinoma may be harder to detect by a mammogram than invasive ductal carcinoma.