Ductal carcinoma in situ (DCIS) is the earliest form of breast cancer, found only within the milk duct in which the cancer started. DCIS is not life-threatening. Doctors sometimes refer to DCIS as precancerous because it is non-invasive. This means that at the time of diagnosis of DCIS, the cancer cells appear to have not yet figured out how to spread outside the duct or to other areas of the body. DCIS is also referred to as Stage 0 breast cancer.
DCIS is associated with an increased risk of getting an invasive cancer, or cancer that spreads to surrounding tissues, in the future. The risk of DCIS coming back is extremely variable and depends on the size and “personality” of the DCIS, as well as the type of treatment. Doctors use the terms high-grade and non-high-grade to describe the “personality” of DCIS. High-grade DCIS poses a greater risk for future problems. Recurrence of cancer can be either non-invasive (not life-threatening) or invasive (potentially serious).
As you might imagine, DCIS can be small and hard to see on a routine screening mammogram. It usually cannot be felt with breast self-exam (BSE). Even when DCIS is identified, the “personality” (high-grade or not) may not be obvious with a mammogram. A study showed that MRI was better than mammography at finding DCIS, and particularly better at finding riskier high-grade DCIS. MRI uses magnetic fields to highlight different kinds of tissues, both normal and abnormal. The results of this study add to other studies that have shown that MRI can, in some circumstances, perform better than routine mammograms in screening for breast cancer. The American Cancer Society recently recommended the use of MRI for screening instead of mammography in certain women at high risk for breast cancer. This does not mean that screening mammograms will be replaced by MRI. But your doctor may decide that in your particular circumstance an MRI should be done instead of, or in addition to, a mammogram.
The main goal of treating DCIS is to reduce the risk of an invasive cancer later on. So in most cases, the treatment for DCIS is breast-conserving surgery (such as lumpectomy). To substantially lower the risk of developing an invasive cancer, most doctors recommend additional treatment with radiation after surgery for DCIS. Treatment recommendations will depend in part on whether the DCIS is high-grade or not. Women with hormone-receptor-positive DCIS may also decide with their doctors that they will have hormonal treatment after surgery to reduce the risk of recurrence and to lower the risk of getting a new cancer. To learn more about DCIS, visit the DCIS – Ductal Carcinoma in Situ section.
This article was made possible by an educational grant from GlaxoSmithKline.