Lobular carcinoma

Lobular carcinoma starts in the lobules. These are groups of glands in the breasts that make milk. Lobular carcinoma can be non-invasive (called lobular carcinoma in situ) or invasive. Non-invasive means that the cancer cells have not spread beyond the gland where they started. Invasive means that the cancer cells have started to spread into the surrounding tissue.

LCIS is a buildup of abnormal cells in the lobules. These cells do not spread outside the lobules into nearby breast tissue. LCIS often develops in many different parts of the breast at the same time. It often develops in both breasts at the same time.

LCIS is most often found when a biopsy is done to check a breast lump or to follow up on an abnormal mammography.

LCIS is neither a true precancerous condition nor breast cancer. It is a sign, or marker, that there is a higher risk of developing breast cancer in the future. Many people who have LCIS do not develop invasive breast cancer.

If you have LCIS and you also have other risks for breast cancer, such as a family history or BRCA gene mutations, you may have a greater risk for developing invasive breast cancer than someone who has LCIS but does not have other risks.

If you are diagnosed with LCIS, it is very important to be screened for breast cancer. Talk to your doctor about a personal plan for screening. This plan may include having mammography more often. You may also want to talk with your doctor about a treatment plan. You may be offered hormone therapy with tamoxifen. Some people consider having surgery to remove the breasts (called a prophylactic mastectomy) if they have other risks for breast cancer as well as LCIS.

The 2 main types of LCIS are classic LCIS and pleomorphic LCIS.

Classic LCIS is when the cells lining the lobules in the breast are small and are all the same size. Classic LCIS is less likely to develop into invasive breast cancer.

If classic LCIS is diagnosed by a core biopsy, you may need to have a surgical biopsy to get a better look at the cells and rule out any other cause for the abnormal cells. Find out more about core biopsy and surgical biopsy.

If only classic LCIS cells are found in the surgical biopsy, you will not need any other surgery or treatment. Your healthcare team will talk to you about a follow-up plan, which will likely include regular screening and close monitoring.

Pleomorphic LCIS is when the cells lining the lobules in the breast are larger and look more abnormal. Pleomorphic LCIS is more likely to become invasive breast cancer. It acts like ductal carcinoma in situ (DCIS).

If pleomorphic LCIS is diagnosed by a core biopsy, you will have a surgical biopsy to remove the cells in the area as well as tissue around it (called a surgical margin). If there are abnormal cells found in the margin, you may have to have more tissue removed until the sample does not have any abnormal cells (called a clear margin).

To lower the risk of invasive breast cancer, some people with pleomorphic LCIS choose to have their breasts removed (called a prophylactic mastectomy).

You may be offered hormone therapy, such as tamoxifen, to also lower the risk of developing invasive breast cancer.

Invasive lobular carcinoma starts in the lobules, and then grows through the lobules and into nearby breast tissue. It can also spread (metastasize) to lymph nodes and other parts of the body. Invasive lobular carcinoma can also be called infiltrating lobular carcinoma. It accounts for about 10% of all invasive breast cancers.

Invasive lobular carcinoma can occur in more than one area of the breast. Doctors may describe this as multifocal or multicentric disease. Invasive lobular carcinoma is more likely to occur in both breasts than other types of breast cancer.

With invasive lobular carcinoma, the cancer cells don’t make a lump. The cancer cells make a thickened area of breast tissue. They may cause changes to the skin on the breast, such as a different texture or dimpling.

This type of cancer is difficult to diagnose with mammography. If your doctor thinks you might have invasive lobular carcinoma, you may have a biopsy. Ultrasound and MRI may also be used to diagnose it.