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Breast Anatomy

What is ductal carcinoma in situ (DCIS)?

Ductal carcinoma in situ (DCIS) is a type of breast cancer. This is also called non-invasive or pre-invasive breast cancer. The cancer cells are found along the sides of the milk duct within the breast. Milk ducts are within each breast and are the tubes that let milk travel from the lobes (made up of lobules) to the nipple openings for breastfeeding.

DCIS is non-invasive, which means that the cancer cells are found only within the milk duct(s) and have not spread through the walls of the ducts and to other nearby tissues in the breast. It is a Stage 0 breast cancer and is treatable. Doctors characterize cancer in stages, using Roman numerals from 0, or zero, to IV, or four. In order to determine the stage of a tumor, doctors must look at the original tumor and determine where it is located, its size, and if it has been noticed in other areas. The lower the stage number, the better chance for successful treatment of the disease and for the best results.

Although DCIS is always considered Stage 0, the tumor can be any size and may be found within several milk ducts inside the breast. With proper treatment, the prognosis is excellent.

How common is ductal carcinoma in situ (DCIS)?

The American Cancer Society expects that 63,960 new cases of DCIS will be found in 2018. Today more and more women are aware of the importance of early detection and are getting mammograms each year. Because of this, the number of cases of DCIS has increased. In addition, mammography technology has greatly improved as well and is better able to detect problems at an earlier stage. An estimated 12.4% of women in the U.S. will develop invasive breast cancer at some time in their lives.

Who is affected by ductal carcinoma in situ (DCIS)?

Most women who get DCIS do not have a family history of breast cancer. Only about 5-10% of breast cancer cases are related to a genetic mutation or family history. Red flags for this include having a family history of breast cancer, especially if the cancer was discovered at a younger age, or before 50 years old. Other red flags for breast cancer that may be related to a genetic mutation include a family history of ovarian cancer, male breast cancer, multiple other cancers in the family and Ashkenazi Jewish ancestry. The most common risk factors for breast cancer include being female and getting older, and these are risk factors that cannot be changed.

Because the tissue in men’s breasts do not fully develop the way that the tissue in women’s breasts do, men do not usually get breast cancer of this type.

What are the symptoms of ductal carcinoma in situ (DCIS)?

DCIS generally has no signs or symptoms. A small number of people may have a lump in the breast or some discharge coming out of the nipple. According to the National Cancer Institute, about 80% of DCIS cases are found by mammography.

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