This page was reviewed under our medical and editorial policy by
Daniel Liu, MD, Plastic and Reconstructive Surgeon
This page was updated on October 18, 2022.
Ductal carcinoma in situ, or DCIS, occurs when cancer cells form in the milk duct cells in the breast. Is DCIS cancer? Yes, it’s the earliest possible stage of breast cancer, also known as intraductal carcinoma or stage 0 breast cancer.
However, being diagnosed with DCIS means the cancer is noninvasive and hasn’t spread through the duct cells into surrounding breast tissue. According to the American Cancer Society, ductal carcinoma in situ accounts for around 1 in 5 new breast cancer diagnoses. Early detection is important because DCIS sometimes progresses to an invasive form of breast cancer if left untreated.
This image shows breast milk ducts and what DCIS may look like:
Often, DCIS doesn’t cause symptoms and is only detected by the patient’s medical team via a mammogram. However, in a small number of patients, some symptoms may occur, including:
Any noticeable changes to a breast should be discussed with a doctor.
The exact cause of DCIS isn’t known, but some factors that may increase the risk of developing the disease.
For example, many patients ask: Is DCIS hereditary? Not necessarily, but a family history of DCIS may increase a person’s risk.
Other DCIS risk factors include:
DCIS diagnosis is made via a breast biopsy, a medical procedure that removes a sample of tissue from the area of the breast where doctors suspect DCIS may be located. The tissue sample is examined under a microscope by a pathologist, who looks for the presence of cancer cells.
If DCIS is detected, the cancer cells are examined and assigned a grade that assesses how fast the cancer is growing and its likelihood of progressing or returning after treatment. The growth potential of ductal carcinoma in situ varies based on three grades:
A DCIS diagnosis may also include information on the cancer’s hormone-receptor status. Additional tests may be used to determine whether the cancer is estrogen-receptor positive or negative—important information that helps the medical team predict whether the cancer may be treated with hormone therapy.
DCIS treatment varies based on the specific type of cancer, but the most commonly used treatment options are:
Surgery: The two types of DCIS surgeries are breast-conserving surgery (BCS), also called a lumpectomy, and mastectomy. BCS involves only removing the tumor and some of the surrounding tissue, while a mastectomy removes the entire breast, especially when the DCIS tumor is large.
Radiation therapy: This treatment uses high-energy X-rays to specifically target DCIS cells. It’s most commonly used in patients who’ve had a lumpectomy, since this treatment lowers the chances that the cancer will return. Breast cancer radiation therapy is rarely used as a standalone treatment for DCIS.
Hormone therapy: Also called endocrine therapy, this approach uses medication to treat types of cancer that are dependent on hormones for their growth. For patients who have hormone-receptor positive DCIS, hormone therapy is sometimes used for up to five years after treatment to reduce the risk of ductal carcinoma in situ returning or a new invasive cancer developing.
