Lobular carcinoma in situ (LCIS)

Lobular carcinoma in situ, also known as LCIS, is a medical condition that causes abnormal cells to grow in the breast glands that are responsible for producing milk, known as the lobules. The abnormal cells remain in the walls of the lobular cells and don’t spread to the breast tissue or other parts of the body.

The three types of LCIS are:

• Classic: The lobular breast cells are smaller and similar in size.
• Florid: The cells lining the lobules have formed a grouping, or mass, sometimes with dead cells in the middle of the mass.
• Pleomorphic: The lobular cells are larger and look abnormal under a microscope.

LCIS isn’t cancer but having the condition may increase the risk of developing invasive breast cancer in the future. According to the American Cancer Society, the risk of invasive breast cancer is seven to 12 times higher if someone was previously diagnosed with LCIS, which is why regular screenings are important.

This guide is designed to help patients know what to expect after an LCIS diagnosis and how it differs from ductal carcinoma in situ (DCIS).

LCIS vs. DCIS

LCIS sounds similar to another breast condition known as DCIS, or ductal carcinoma in situ. However, they are different diseases.

DCIS, also known as stage 0 breast cancer or intraductal carcinoma, is a type of cancer caused when cancer cells have developed in the breast ducts, but the cancer hasn’t spread into the breast tissue.

However, DCIS may sometimes become an invasive breast cancer, which has the possibility of spreading to other parts of the body. In contrast, LCIS is a separate condition that isn’t cancerous and doesn’t become invasive breast cancer.

Lobular carcinoma in situ symptoms and diagnosis

Unlike some other health conditions, LCIS generally doesn’t cause symptoms, so patients may not notice bodily changes or signs. It also doesn’t usually show up on mammogram tests—a diagnostic tool that uses an X-ray to take pictures of the breast to screen for breast cancer.

Instead, LCIS is most often diagnosed when breast biopsies are performed for other reasons. In a biopsy, another type of diagnostic test, the doctor takes a cell sample from the breast and examines it under a microscope, looking for signs of abnormal cells.

Lobular carcinoma in situ treatment and reducing breast cancer risk

Because LCIS isn’t a type of cancer, active treatment isn’t typically needed. Treatment may also depend on the patient’s personal preferences.

In some cases, the patient’s medical team may remove the tissue via either excisional biopsy or surgery. Hormone medication may be recommended as a preventative therapy to lower the risk of cancer in the future.

Increased observation and monitoring may be recommended, so if breast cancer does develop, it may be caught early. This approach typically involves visiting the doctor every six to 12 months for examinations and breast MRIs.

Patients may also speak to their care team about lifestyle changes they can make to lower the risk of breast cancer. These may include:

• Maintaining a healthy weight and getting enough exercise each week
• Limiting or avoiding alcohol
• Undergoing genetic testing to help better understand risk level, if the patient has a family history of breast cancer

Learn about other possible breast cancer causes and risk factors