Breast-conserving therapy for primary Ductal Carcinoma in Situ in The Netherlands: A multi-center study and population-based analysis.

Objective: The aim of this study was to analyse the efficacy of breast-conserving therapy (BCT) for women with primary DCIS in a population-based setting.

Methods: Data were used from five Radiotherapy centres in The Netherlands from 2000 to 2010, all treated with BCT. Of all the cases, 59.2% received a boost of radiotherapy after their whole breast irradiation (WBI), irrespective of margin status.

Results: A total of 1248 cases with primary DCIS were analysed. The 10-years LRFS was 92.9%. Age ≤50 years and a positive margin were significantly related to local relapse free survival (LRFS). Having a boost had no impact on LRFS, showing a nearly equal recurrence pattern in patients with and without a boost. Separate analyses were done on patients who had received and not received a boost of radiotherapy after WBI. We noted 9.1% contra-lateral breast tumours. The 10-years disease specific survival (DSS) rate was 99.0%.

Conclusions: DCIS of the breast and treated with BCT results in excellent LRFS and DSS. Primary surgical lumpectomy with negative margins followed by WBI seems to be the treatment of choice in DCIS treated with BCS with respect to IBTR.