The Difference Between Ductal Carcinoma In Situ (DCIS) and Invasive Breast Cancer

Ann Romney recently reported that she was being treated for ductal carcinoma in situ (DCIS). The headlines read that she was being treated for breast cancer, but Mrs. Romney was very clear in her statement that DCIS is technically a precancer because it is not invasive.
DCIS is often referred to as an early stage of breast cancer, but there is an important distinction. DCIS differs from invasive cancer in that it stays in the breast ducts. It is the capacity to spread, or metastasize, that makes invasive breast cancer dangerous. The concern with DCIS – a noninvasive cancer — is that it can transform to become invasive breast cancer.
Scientists believe that DCIS would not always progress to breast cancer. Once detected, though, it is removed surgically to eliminate the possibility that it would become cancer because no one can predict which women would have it transform and which would not.
DCIS is a serious condition that requires treatment, but many women face greater anxiety than they should because it is referred to as an early stage of breast cancer. The implication is that it is the first of an inevitable series of stages. Instead, it is a precancerous lesion that could undergo a transformation to become invasive. The distinction is important, but it is often lost.
Depending on how extensive the DCIS is and what its characteristics are, it may be removed with a lumpectomy or a mastectomy and may require radiation. The risk of recurrence is very low.
There are sometimes stories in the news about women with DCIS choosing to have both breasts removed to prevent the possibility of getting breast cancer. Having a bilateral prophylactic mastectomy for DCIS is more than is needed, though it might be considered when a woman has additional risk factors like a faulty BRCA gene or a very strong family history of breast cancer.
Mrs. Romney’s health care providers deserve credit for being clear about what her diagnosis meant. Too many women who are diagnosed with DCIS do not realize that it has important differences from invasive breast cancer. With proper treatment and attention to lifestyle factors that reduce breast cancer risk, future problems are unlikely.