Lobular Carcinoma (Invasive and In Situ)

Most breast cancers start in the ducts of the breasts, but some begin in the glands that produce milk, called the lobules.

These are:

  • Lobular carcinoma in situ (LCIS), also called lobular neoplasia
  • Invasive lobular carcinoma (ILB), also called infiltrating lobular carcinoma

The symptoms, diagnosis, and treatment for each are different.

Lobular Carcinoma in Situ

LCIS isn’t cancer, but it’s thought to be a sign that breast cancer may develop. With this condition, there are abnormal cells in multiple lobules of the breasts, but these cells rarely spread to other parts of the breast or body. The phrase "in situ" means "in its original place."

Areas of lobular carcinoma in situ are sometimes seen in both breasts.

Even though this condition doesn’t spread, it’s important to keep an eye on it. Between 20% to 40% of women with this condition will develop a separate invasive breast cancer -- one that will grow outside its original location -- within the next 15 years. Most of the time, these later cancers begin in the milk ducts, rather than the lobules.

How is lobular carcinoma in situ diagnosed?

You often won’t have any symptoms with LCIS. Many times, it’s not even found by routine mammograms. Unlike other breast cancers and related conditions, LCIS doesn’t cause lumps. It’s most commonly diagnosed when a biopsy is done for another condition.

The biopsy findings for LCIS can be very similar to an actual breast cancer called ductal carcinoma in situ. Because of this, you may want to ask for a second opinion to confirm your diagnosis.


How is lobular carcinoma in situ treated?

Some women with LCIS won’t need immediate treatment with surgery or medicines. Instead, the doctor may recommend keeping a close eye on your condition. That means regular breast self-exams, office visits, and routine mammograms or other tests such as MRIs.

If you have a family history of breast cancer and are at an increased risk, your doctor may discuss the use of medications such as anastrozole (Arimidex), exemestane (Aromasin), raloxifene (Evista), or tamoxifen (Nolvadex). These drugs may lower the chance that you’ll develop invasive breast cancer.

Sometimes surgery to remove tissue in the area of the LCIS is performed.

Some women at higher risk opt to undergo preventive surgery called a prophylactic mastectomy. The procedure removes one or both breasts. Doing so can significantly reduce the risk of breast cancer in the future.

Invasive Lobular Carcinoma

ILC is the second most common form of invasive breast cancer. It begins in one of the breast lobules, then spreads to other parts of the breast. It’s more likely to be found in both breasts than other types of breast cancer. It can also spread to other areas in the body.

How is invasive lobular carcinoma diagnosed?

You might not feel a distinct lump. Instead, you may feel a thickened area or a hardening in part of your breast. It often occurs in the area above your nipple toward your armpit. Your skin of your breast or nipple may dimple.

Often, ILC can’t be found by a mammogram. If you have a suspicious area, your doctor should order a biopsy to analyze cells. 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.

The biopsy will help your doctor decide whether you have invasive lobular carcinoma and how aggressive it may be.

Invasive lobular carcinoma spreads. So your doctor may recommend additional tests to search for cancer in other parts of your body. These tests may include:

  • CT scan. It's a powerful X-ray that makes detailed pictures inside your body.
  • PET scan . Used together with a CT scan, this test can help find cancer in lymph nodes and other areas.
  • MRI . It uses strong magnets and radio waves to make pictures of the breast and other structures inside your body.
  • Bone scan. A radioactive substance called a tracer is injected into your arm, and pictures are taken to find out if cancer may have traveled to your bones.
  • Chest X-ray: It uses radiation in low doses to make images of structures inside your chest.

Your doctor will also take samples from your lymph nodes in the armpits to check for cancer. This is called axillary lymph node dissection.

The results of your exams will determine the stage of your breast cancer and the best treatment options.


How is invasive lobular carcinoma treated?

Most women with invasive lobular carcinoma have surgery to remove the cancer from the breast. In most cases, the cancer can be taken out without removing the entire breast. It will depend on the size of your tumor and how much it has spread throughout your breast and surrounding lymph nodes.

Your doctor may also recommend treating it with chemotherapy, radiation therapy, hormone therapy, or some combination of the three. Chemotherapy and hormone 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. There are hormone treatments to specifically target these cells.

Other targeted therapy may be helpful if the cancer is HER2-positive.

WebMD Medical Reference Reviewed by Laura J. Martin, MD on July 17, 2017



Breastcancer.org: “Lobular carcinoma in situ;” “Invasive lobular carcinoma;” ”Bone Scans;” “LCIS and Breast Cancer Risk;” ”Treatments for LCIS;” “Test for Diagnosing ILC;” and “Systemic Treatments for ILC: Chemotherapy, Hormonal Therapy, Targeted Therapies.”

Breast Cancer Network of Strength: “Lobular carcinoma in situ” and “Infiltrating lobular carcinoma.”

National Cancer Institute: “Lobular carcinoma in situ.”

American Cancer Society: “What is breast cancer?” and "Special Section: Breast Carcinoma in Situ."

College of American Pathologists: “Lobular carcinoma in situ“ and "Invasive lobular carcinoma.”

MedlinePlus: “Tamoxifen.”

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