The breast contains lobes where milk is made. LCIS is a condition where there are abnormal changes in the cells that line the lobes. LCIS is also called lobular neoplasia.
LCIS is not a cancer. The abnormal changes mean that a woman has a higher than average risk of developing breast cancer later in life.
Even if LCIS is only diagnosed in the left or right breast, the risk of developing cancer is similar in both breasts. Some women have LCIS in both breasts. But most women with LCIS do not develop breast cancer.
LCIS is more common in women who have not been through the menopause. It is more common in women aged between 40 and 50.