Breast Cancer Health Center

Lobular Carcinoma (Invasive and In Situ)

What is invasive lobular carcinoma?

Invasive lobular carcinoma is the second most common form of invasive breast cancer. It accounts for 5% to 10% of invasive breast cancers. The condition typically begins in one of the breast lobules. It then spreads to other parts of the breast. For about one in three women, invasive lobular carcinoma is present in both breasts. It can also spread to other areas in the body.

How is invasive lobular carcinoma diagnosed?

If you have invasive lobular carcinoma, you might not be able to feel a distinct lump. Instead you may feel a thickened area or a hardening in part of your breast. This often occurs in the area above your nipple moving in the direction of your armpit.

If your tumor is large, it may cause the skin of your breast or nipple to become dimpled over the area of cancer.

Often, invasive lobular carcinoma cannot be detected by a mammogram. If you have a suspicious area, your doctor should order a biopsy to analyze cells from the thickened area of your breast. Most biopsies use a needle to extract a sample of cells from the breast. In some instances, though, larger samples or the entire tumor will be removed for analysis. 

Based on the biopsy results, your doctor will be able to determine whether you have invasive lobular carcinoma and how aggressive it is.

Invasive lobular carcinoma can spread. So your doctor may recommend additional tests. The purpose will be to search for the presence of cancer in other parts of your body. These tests may include:

• CT scan
• MRI
• PET scan
• Bone scan
• Chest X-ray

Surgery to check the lymph nodes in the armpits for cancer (axillary lymph node dissection) is always performed in the presence of invasive lobular carcinoma.

Your doctor will use the results of your exams to determine the stage of your breast cancer. The doctor will also use the results to design a treatment plan.

How is invasive lobular carcinoma treated?

The majority of women with invasive lobular carcinoma have surgery. The surgeon removes the cancer from the breast. In most cases, the cancer can be removed with breast-conserving procedures. Those procedures remove only a portion of one or both breasts. How much is removed will depend on the size of your tumor. It will also depend on the extent of its spread throughout your breast and surrounding lymph nodes.

Most doctors will also recommend treating invasive lobular carcinoma with chemotherapy, radiation therapy, endocrine therapy, or some combination of the three. Chemotherapy and endocrine therapy are systemic treatments. They target cancer cells throughout your entire body. Radiation specifically focuses on the area around your breast cancer.

Cells in invasive lobular carcinoma often contain estrogen and progesterone receptors. These make them prime targets for anti-estrogen endocrine therapy.