Ductal carcinoma in situ (DCIS) is a non-invasive form of breast cancer, meaning that the abnormal cells are contained within the milk ducts of the breast and have not invaded the nearby breast tissue. DCIS cannot spread to the lymph nodes or other parts of the body. Therefore, it is considered stage 0 breast cancer. Although it is not life-threatening, treatment for this stage of disease is recommended because DCIS can turn into invasive breast cancer, which could then be life-threatening. The goal of treatment for DCIS then is to prevent development of invasive breast cancer. It is similar to removing polyps in the colon, which is performed routinely because colon polyps can turn into colon cancer.
DCIS doesn't typically cause symptoms. However, on occasion DCIS can present as a breast lump or bloody nipple discharge.
DCIS is usually found on a mammogram and appears as small clusters of calcifications that have irregular shapes and sizes. Prior to routine screening mammogram, we didn’t even know this stage of breast cancer even existed.
If abnormal calcifications are seen on a mammogram, a needle biopsy is recommended to determine if the calcifications are associated with a benign process or a cancerous process in the breast. A needle biopsy prior to surgery is the recommended method of obtaining a diagnosis of breast cancer.
Patients are often concerned that the needle biopsy will disrupt and disseminate cancer cells, but this is not the case. Patients who are diagnosed with breast cancer by needle biopsy are not diagnosed at higher stages and do not have a worsened outcome than patients who are diagnosed by a surgical biopsy. Therefore, a needle biopsy is the preferred approach for diagnosing breast cancer.
Without treatment DCIS may turn into invasive breast cancer, so DCIS is treated to prevent invasive cancer from forming. Treatment of DCIS may include surgery to remove only the abnormal cells (lumpectomy) followed by possible radiation or surgery to remove all breast tissue (mastectomy). Because DCIS is not an invasive cancer and cannot spread to other parts of the body, whole body treatments, like chemotherapy, are not indicated for this stage of disease. Hormone-blocking therapy may be discussed to reduce the risk of the DCIS returning in the breast because half of the time DCIS can recur as an invasive cancer but it is not necessary for treatment of DCIS. Active monitoring of DCIS as an alternative to surgery is also being studied in a clinical trial.
With treatment, the prognosis of DCIS is excellent.