Final results from a multicenter prospective study (?JROSG 05-5) on postoperative radiotherapy for patients with ductal carcinoma in situ with an involved surgical margin or close margin widths of 1 mm or less

This multicenter prospective study (?japanese radiation oncology study group: jrosg 05-5) aimed to evaluate the effectiveness of postoperative radiotherapy (port) in patients with ductal carcinoma in situ (dcis) with an involved surgical margin or close margin widths of ≤1 mm or less. port consisted of whole-breast irradiation (50 gy in 25 fractions) followed by boost irradiation (10 gy in 5 fractions). eligibility criteria were as follows: (i) dcis without an invasive carcinoma component,(ii) age between 20 and 80 years old,(iii) involved margin or close margin widths of ≤1 mm,(iv) refusal of re-resection,(v) performance status of 0-2,and (vi) written informed consent. the primary endpoint was ipsilateral breast tumor recurrence (ibtr),and secondary endpoints were overall survival (os),relapse-free survival (rfs),recurrence patterns,and adverse events. a total of 37 patients from 12 institutions were enrolled from january 2007 to may 2009. the median follow-up time was 62 months (range,28-85 months). the median pathological tumor size was 2.5 cm (range,0.3-8.5 cm). of the 37 patients,21 had involved margins,and 16 had close margins. the 5-year ibtr,os and rfs rates were 6% (95% confidence interval [ci]: 2-21),97% (95% ci: 83-99) and 91% (95% ci: 77-97),respectively. two patients developed local recurrence at the original site after 39 and 58 months. no severe adverse events were found. our study suggests that this port regimen could be a treatment option for patients with dcis with involved margin or close margin who don't desire re-resection. © 2015 the author 2015. published by oxford university press on behalf of the japan radiation research society and japanese society for radiation oncology.