Local control with conventional and hypofractionated adjuvant radiotherapy for ductal carcinoma in-situ: is there a difference in outcome?.

Abstract

Abstract Abstract #1162 Purpose
 Trials of adjuvant whole breast radiotherapy (WBRT) following breast-conserving surgery for invasive breast cancer indicate equivalent efficacy and morbidity for conventional and hypofractionated treatment. WBRT for ductal carcinoma in-situ (DCIS) improves local control, however an optimal dose fractionation remains undefined. Our group policy allowed for the use of both schedules, therefore we compared local control in women with DCIS following breast-conserving surgery.
 Methods
 Two hundred and sixty six patients treated between January 1999 and December 2004 with conventional (50 Gy/25 fractions) or hypofractionated (42.4 Gy/16 daily fractions or 40 Gy/16 fractions + 12.5 Gy/5 fraction boost) radiotherapy schedules to the whole breast after breast-conserving surgery for DCIS were identified and retrospectively reviewed. Treatment schedules were evaluated for outcomes in terms of ipsilateral breast recurrence.
 Results
 The median age at diagnosis 56.7 years (range 32.2-83.8 years), and 82% (218 patients) presented with mammographic abnormality. Median tumour size was 1.5 cm (range 0.4-10 cm), grade 3 tumours were present in 105 women (39%), and comedonecrosis in 145 (55%). Fifty-one patients (19%) had multifocal disease. Median follow-up was 45.1 months (range 0.7-106.8 months). Prognostic features were well matched in both groups.
 One-hundred and four patients (39%) were treated with conventional and 162 (61%) with hypofractionated WBRT. There were a total of 14 confirmed local recurrences in the previously radiated breast. Six recurrences occurred in the 104 (5.8%) patients treated with a conventional schedule and 8 of 162 (4.9%) patients treated with a hypofractionated schedule. Actuarial risk of recurrence at 4 years was 7% with hypofractionated WBRT and 5% with a standard schedule (p=0.85).
 
 Eight patients recurred with DCIS and 6 with invasive carcinomas, all 14 were treated surgically with adjuvant treatment as indicated clinically, 1 patient with clinical recurrent disease refused biopsy and further conventional treatment. Univariate analysis showed a trend to increased risk of recurrence with grade 3 tumours (10% at 4 years vs. 3% for grade1/2, p=0.053) and presence of comedonecrosis (8% vs. 2%, p=0.096), but not multi-focal disease (7% vs. 5%, p=0.78).
 Conclusions
 Hypofractionated adjuvant WBRT schedules following breast-conserving surgery for DCIS have comparable local control rates to a conventional radiation schedule. Hypofractionated WBRT is more convenient for patients, has equivalent morbidity and should be considered in this patient group. Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 1162.