Lobular carcinoma starts in the lobules of the breast, where breast milk is produced. The lobules are connected to the ducts, which carry breast milk to the nipple.
Lobular Carcinoma In-Situ (LCIS)
LCIS is an area (or areas) of abnormal cell growth that increases a person’s risk of developing invasive breast cancer. Despite the fact that its name includes the term “carcinoma,” LCIS is not a true cancer. However, it is sometimes classified as a type of non-invasive breast cancer. It begins in the lobules (milk-producing glands at the end of the milk ducts), but it does not grow through the wall of the lobules.
Carcinoma refers to any cancer that begins in the skin or other tissues that cover internal organs, such as breast tissue. In situ or “in its original place” means that the abnormal growth remains inside the lobule and does not spread to surrounding tissues. People diagnosed with LCIS tend to have more than one lobule affected.
LCIS is an indication that a person is at higher-than-average risk for getting breast cancer at some point in the future. For this reason, some experts prefer the term “lobular neoplasia” instead of “lobular carcinoma.” A neoplasia is a collection of abnormal cells.
LCIS is usually diagnosed before menopause, most often between the ages of 40 and 50. Less than 10 percent of women diagnosed with LCIS have already gone through menopause. LCIS is extremely uncommon in men.
It is unknown exactly how many people are affected by LCIS because it does not cause symptoms and usually does not show up on a mammogram. It tends to be diagnosed as a result of a biopsy performed on the breast for some other reason.
Infiltrating (Invasive) Lobular Carcinoma (ILC)
This cancer is the second most common type of breast cancer after invasive ductal carcinoma (cancer that begins in the milk-carrying ducts and spreads beyond it).
All together, “invasive lobular carcinoma” refers to cancer that has broken through the wall of the lobule and begun to invade the tissues of the breast. Over time, invasive lobular carcinoma can spread to the lymph nodes and possibly to other areas of the body. ILC usually appears as a subtle thickening in the upper-outer quadrant of the breast.
Although invasive lobular carcinoma can affect women at any age, it is more common as women grow older. ILC tends to occur later in life than invasive ductal carcinoma — the early 60s as opposed to the mid- to late 50s.
Some research has suggested that the use of hormone replacement therapy during and after menopause can increase the risk of ILC.
ILC can spread (metastasize) to other parts of the body. Invasive lobular carcinoma may be harder to detect by a mammogram than invasive ductal carcinoma.