In addition to invasive breast cancers, there are two types that are noninvasive, meaning the cancer cells are contained in the ducts or lobules of the breast.

In ductal carcinoma in situ, also called DCIS, abnormal cells are found in the lining of the milk ducts, the tubes that carry milk to the nipple. It is also called intraductal carcinoma.

Unlike invasive disease, the cancer in DCIS has not broken through the walls of the milk ducts to surrounding healthy breast tissue. DCIS is stage 0, meaning the cancer remains in the area where it began. DCIS is the most common type of in situ breast cancer.

Another noninvasive breast cancer is lobular carcinoma in situ (LCIS), abnormal cell growth that does not spread beyond the breast’s milk-making glands, or lobules. LCIS is much less common than DCIS. Although LCIS is not considered cancer and is not an immediate threat to your health, it is a marker that you have a higher than average risk of developing breast cancer in either breast in the future.

Diagnosing noninvasive breast cancer

DCIS is usually diagnosed through a mammogram and biopsy. But LCIS can be harder to detect.

Because LCIS often doesn’t have microcalcifications, very small pieces of calcium that form in other types of breast cancer cells, it may not show up on a mammogram. LCIS is usually diagnosed after you have a biopsy for another reason, such as checking an abnormal breast lump.

If you are diagnosed with LCIS after a needle biopsy, your doctor may recommend a surgical biopsy to make sure you don’t have DCIS or invasive breast cancer.

Treating DCIS

Although not life-threatening, DCIS that is not well treated can become invasive breast cancer. Having DCIS can also increase your risk of developing invasive breast cancer later in life. If DCIS is found in addition to an invasive breast cancer diagnosis, you will be treated based on the stage of the invasive cancer.

There is overlap between treatment for DCIS and invasive breast cancer. Your surgeon will talk with you about the type of surgery that makes most sense for you, based on:

  • The amount of DCIS
  • The locations of DCIS
  • The size of your breast

Your surgeon may recommend a lumpectomy, where only the area of DCIS and a small rim of surrounding tissue are removed. After, you would have radiation therapy. Sometimes, if the area of DCIS is too large or there are several areas of DCIS in different parts of your breast, your surgeon may recommend a mastectomy, removing the entire breast. Radiation therapy is generally not needed after mastectomy for DCIS.

Then you may receive hormonal therapy, like tamoxifen, if the DCIS is hormone receptor-positive.

There are no tests available today that can tell the difference between DCIS that will progress into invasive breast cancer and DCIS that will not. Because of this, it’s possible some women with DCIS get more treatment than they need. Researchers are looking for ways to predict risk of DCIS recurrence or progression. Until then, your doctor is likely to recommend you have treatment to protect you from the risk the DCIS will come back or become an invasive breast cancer.

Treating LCIS

LCIS is not an immediate threat to your health. It doesn’t require standard breast cancer treatment, but you may have follow-up visits to watch for signs of invasive breast cancer. Your doctor might also advise that you make lifestyle changes, take medicines or undergo preventive surgery to reduce your risk of developing breast cancer.


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Reviewed and updated: August 31, 2015

Reviewed by: Pallav K. Mehta, MD


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