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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:

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  • 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 will develop. With this condition, there are abnormal cells in the 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."

Most women who are diagnosed with LCIS haven’t yet gone through menopause. Often, multiple lobules are affected. About a third of the time, there are areas of lobular carcinoma in situ 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?

Most 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.

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.

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