The management of ductal carcinoma in situ of the breast: a screened population-based analysis.
BACKGROUND: A recent SEER study identified significant variations in the care of women with DCIS, yet several potential confounding variables were not included. We report a patterns of care study of women with DCIS to better understand the gap between evidence-based knowledge and the management of DCIS. METHODS: We studied all cases of DCIS diagnosed through the Ontario Breast Screening Program from 1991 to 2000. Data was obtained by database linkage and chart abstraction. A logistic regression model using generalized estimating equations to adjust for clustering was used. RESULTS: About 320,236 women were screened and 727 individuals were diagnosed with DCIS. The rate of mastectomy was 30% and was associated with multifocality (OR: 3.5 [1.7, 7.1], P = 0.0005), tumor size (OR: >2 cm vs. 1 cm (OR: 2.4 [1.3, 4.4], P = 0.006). Half of cases with margins <1 cm did not receive XRT. CONCLUSIONS: Our study corroborates previous reports on the persistent rates of mastectomy and axillary nodal dissection and the limited use of XRT in the treatment of DCIS.