Lobular carcinoma starts in the groups of glands that make milk (called lobules). It may be non-invasive (called lobular carcinoma in situ) or invasive.
Lobular carcinoma in situ (LCIS)
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 a woman is at a higher risk of developing breast cancer in the future. Many women with LCIS do not develop invasive breast cancer.
Doctors do not yet know how to identify which women with LCIS will eventually develop invasive breast cancer. They think that women with LCIS who also have other risk factors for breast cancer, such as a family history or BRCA gene mutations, may have a greater risk for developing invasive breast cancer than women with LCIS who do not have other risk factors. Because of this increased risk, it is very important for women with LCIS to be screened for breast cancer.
If you are diagnosed with LCIS, talk to your doctor about a personal plan for screening for breast cancer. 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 hormonal therapy with tamoxifen (Nolvadex, Tamofen). Some women may consider having surgery to remove the breasts (called a prophylactic mastectomy) if they have other risk factors for breast cancer as well as LCIS.
Invasive lobular carcinoma
Invasive, or infiltrating, lobular carcinoma accounts for about 10% of all invasive breast cancers.
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 occur in more than one area of the breast (called multifocal, or multicentric, disease). It 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. They grow in a single strand into the fatty tissues of the breast. 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 are also used to diagnose it.