Breast Ductal Carcinoma in Situ: What to Do?

Mammographic screening is used for the early detection of breast cancers. However, controversy continues to rage as to how effective it is in identifying early cancers whose treatment would cure the disease or extend life span. A recent study published in the August 20 issue of JAMA Oncology extends the controversy. About 25% of breast cancers identified by mammography are ductal carcinoma in situ (DCIS). This cancer is confined to the milk ducts of the breast and do not invade into the duct or adjacent tissues (see figure). The study, authored by investigators from Toronto, looked at 10- and 20-year breast cancer-specific mortality in >100,000 women who had been diagnosed with DCIS. Overall the risk of dying from breast cancer was low (<1%), although that risk was higher in some subgroups (e.g. very young, African-American). Importantly, it did not appear that aggressive therapy of DCIS (lumpectomy + radiation therapy) led to a reduction in mortality. While DCIS does appear to be a risk factor for invasive cancer, aggressive therapy may not, in general, be warranted and low- to intermediate-grade DCIS may not be a target for screening and early detection. The controversies continue!