The present study was designed to compare the effectiveness of treatment methods for ductal carcinoma in situ (DCIS). Few comparative effectiveness studies of DCIS have been performed using detailed information on clinical factors and treatment. The study included 994 women diagnosed with DCIS from 1985 to 2000 in New York and Michigan. The authors used medical records to collect detailed data concerning clinical and nonclinical factors, pathology, treatment, and long-term outcome data.
Type of treatment and margin status both were found to be strong predictors of long-term disease-free survival. Women who were treated with breast conserving surgery (typically lumpectomy) without receiving radiation treatment or who had close or positive surgical margins without further treatment were less likely to survive. Patient outcomes differed substantially by surgeon. The surgeon accounted for 15% to 35% of subsequent five-year ipsilateral recurrence (i.e., in the same breast that was treated) and for 13% to 30% of 10-year ipsilateral recurrence rates. The overall differences in predicted five-year disease-free survival rates for mastectomy (99.3%), breast conserving surgery with radiation treatment (94.5%), and breast conserving surgery without radiation (82.4%) were statistically significant. Similarly, each of the differences at 10 years was statistically significant. The authors conclude that their work demonstrates the contributions of treatments and margin status to long-term disease-free survival and the link between surgeons and these key measures of care. Although to some extent variation by surgeon could be influenced by patients' preferences, the extent of the variation and its contribution to long-term health outcomes are troubling. Further work is required to determine why some women with positive margins receive no additional treatment and why margin status and receipt of radiation treatment vary by surgeon.