About one fifth of breast cancers detected through routine mammograms are at an early stage; some cells in ducts within the breast have become cancerous, but have not yet started spreading into the surrounding tissue.
This is known as ductal carcinoma in situ breast (DCIS) or stage zero cancer. Such cancers can be easily removed surgically. However, some women can subsequently develop a second breast cancer after having a DCIS breast cancer removed and this may (in a low proportion of patients) be invasive and ultimately fatal.
Steven Narod MD and colleagues analysed data in the Surveillance, Epidemiology and End Results (SEER) 18 registries database to see if they could identify factors predictive of mortality after a DCIS diagnosis.
The study included data from 108,196 women diagnosed with DCIS between 1988 and 2011. The average age at diagnosis was 54 years and the women had follow-up data covering an average of 7.5 years.