Lobular breast cancer (also called invasive lobular carcinoma) is breast cancer that starts in the milk-producing gland, or lobules, of your breast and has spread into surrounding breast tissue. It can be cured if caught early. Left untreated, lobular breast cancer spreads to nearby lymph nodes, and then to other areas of your body.

Lobular carcinoma in situ (LCIS) is not breast cancer; it is a condition where abnormal cells are found in the milk glands, or lobules, of the breast and have not invaded any other area. Invasive lobular carcinoma (ILC) is cancer that began growing in the lobules (milk glands) of the breast and is invading the surrounding tissue.

Lobular makes up about 15% of all breast cancers, and is the second most common form of breast cancer. Unlike Ductal Breast Cancer, Lobular Breast Cancer or Invasive Lobular Cancer (ILC) grows in a line or as single cells and rarely forms a lump.

Lobular carcinoma in situ (LCIS) is an uncommon condition in which abnormal cells form in the milk glands (lobules) in the breast. Lobular carcinoma in situ (LCIS) isn't cancer. But being diagnosed with LCIS indicates that you have an increased risk of developing breast cancer. LCIS usually doesn't show up on mammograms.