Types of Breast Cancer

Even though we commonly refer to breast cancer as one disease, there are actually several different types of breast cancer.  One of the first things your doctor should share with you after confirming that you have breast cancer is the type of breast cancer you have.  If the doctor does not volunteer this information, then by all means, ask him/her.  The type of breast cancer you have will dictate what type of treatment options are available to you.  Knowing what type of cancer you have will make it easier for you to research your treatment options and make informed decisions with your doctor. 

Here's a list of the general categories:

Ductal carcinoma in situ (DCIS): This is the most common type of non-invasive breast cancer. DCIS means that the cancer is only in the ducts. It has not spread through the walls of the ducts into the tissue of the breast. Nearly all women with cancer at this stage can be cured. Often the best way to find DCIS early is with a mammogram. If there are areas of dead or dying cancer cells (called tumor necrosis) within the biopsy sample (when tissue is taken out to be looked at in the lab), the tumor is likely to grow and spread quickly (be more aggressive).  See A, C, & D on the diagram.

Lobular carcinoma in situ (LCIS): This begins in the milk-making glands (lobules) but does not go through the wall of the lobules. It is not a true cancer, but having LCIS increases a woman's risk of getting cancer later. For this reason, it's important that women with LCIS make sure they have regular mammograms and doctor visits.  See A, B & C on the diagram.

Invasive (or infiltrating) ductal carcinoma (IDC): This is the most common breast cancer. It starts in a milk passage (a duct), breaks through the wall of the duct, and invades the tissue of the breast. From there it may be able to spread (metastasize) to other parts of the body. It accounts for about 8 out of 10 invasive breast cancers. See sections A,B & C on the diagram.

Invasive (infiltrating) lobular carcinoma (ILC): This cancer starts in the milk glands (the lobules). It can spread (metastasize) to other parts of the body. About 1 out of 10 invasive breast cancers are of this type.

Inflammatory breast cancer (IBC): This uncommon type of invasive breast cancer accounts for about 1% to 3% of all breast cancers. Usually there is no single lump or tumor. Instead, IBC makes the skin of the breast look red and feel warm. It also makes the skin look thick and pitted something like an orange peel. The breast may get bigger, hard, tender, or itchy. In its early stages, inflammatory breast cancer is often mistaken for infection. Because there is no defined lump, it may not show up on a mammogram, which may make it even harder to catch it early. It usually has a higher chance of spreading and a worse outlook than invasive ductal or lobular cancer.

A ducts, B lobules, C dilated section of duct to hold milk, D nipple, E fat, F pectoralis major muscle, G chest wall/rib cage [2]

REFERENCES
[1] Adapted from the American Cancer Society, Breast Cancer: early detection http://www.cancer.org/Cancer/BreastCancer/DetailedGuide/breast-cancer-what-is-breast-cancer
[2] Diagram adapted from Breast Cancer.org http://www.breastcancer.org/pictures/types/

Last Medical Review: August 2010