Abstract P5-16-03: Influence of radiotherapy boost in patients with ductal carcinoma in situ of breast cancer: A multicenter, retrospective study in Korea (KROG 11-04)

Abstract

Abstract Purpose We aimed to estimate the effect of boost radiotherapy on local relapse-free survival (LRFS) in patients with ductal carcinoma in situ (DCIS) of breast cancer. Material and Methods We included patients from 8 institutions who met the following inclusion criteria: having tumor status Tis, age 18 years or older at diagnosis, having had breast conserving surgery (BCS) and radiotherapy within 12 weeks after surgery. From January 1995 through December 2006, 594 patients with DCIS breast cancer treated with BCS and radiotherapy were analyzed retrospectively in a study by Korean Radiation Oncology Group (KROG). All patients received whole breast radiotherapy (median 5040 cGy) after BCS. Among them, 154 patients (25.9%) received boost radiotherapy (median 1000 cGy) after whole breast radiotherapy. Patients who received boost radiotherapy had higher tumor grade, more comedo pattern and less papillary pattern. Other patients’ or tumor characteristics were not statistically different between boost group and no boost group. Results After median follow-up of 89 months (range 26-200), 5 year and 10 year LRFS was 98.3% and 95.6%. There was no statistically significant difference of LRFS between boost group and no boost group. Local relapse free survival according to boost radiotherpay 5-year LRFS* (%)10-year LRFS (%)p-value**Boost group98.196.20.626No boost group98.495.4 *Local relapse free survival, **Log-rank test Nineteen (3.2%) patients had ipsilateral breast recurrences, of whom, 12 patients had invasive breast cancer and 7 had DCIS. Positive HER2 receptor was associated with higher invasive recurrences. Ipsilateral breast recurrences according to HER2 receptor TotalHER2 receptor (+)HER2 receptor (-)p-value*Ipsilateral breast121110.017Invasive8800.023DCIS**4310.642*Fisher's exact test, **Ductal carcinoma in situ Nine (1.5%) patients developed contralateral breast cancer, of whom, 6 were invasive breast cancer and 3 were DCIS. On multivariate analysis, only margin status was a significant prognostic factor for LRFS. Conclusion In the absence of randomized trials, boost radiotherapy could not decrease local recurrence in DCIS of breast cancer after BCS and radiotherapy. In addition, patients with positive HER2 receptor would need further treatment like target agent, trastuzumab. NSABP B-43 study result would answer the question. Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P5-16-03.