ESTRO 36 Abstract Book

S92 ESTRO 36 _______________________________________________________________________________________________

Purpose or Objective To examine 5-year rates of local control for breast cancer patients with local relapses after second conservative surgery and accelerated partial breast irradiation (APBI). Material and Methods Eligibility included local relapses of breast cancer <3 cm in size after lumpectomy with negative surgical margins. The APBI dose delivered was 34 Gy in 10 twice-daily fractions over 5 days for high-dose-rate. This analysis focuses on ipsilateral breast recurrence(LBR), regional recurrence (RR), and distant metastases (DM), disease- free and overall survival. Results The median follow-up was 49.6 months (5-98m). Fithty two patients (p) were accrued from Sep 2008 to August 2015. Histology: Intraductal carcinoma 15 p, Ductal carcinoma 31 p, Lobulillar carcinoma: 5 p; Papilar carcinoma : 1p; 50 p had T1 tumors and 2 p had T2. Seventy-five percent were estrogen receptor and/or progesterone receptor positive. There have been 4 local breast recurrences, 1 regional recurrence (RR), and 1 distant metastases (DM), The 5- year Local Recurrence Disease Free rate was 91.6%. The 5-year Disease Free Survival and Overall Survival rates are 87 % and 100%, respectively. Conclusion This prospective trial studying APBI in local relapses of Breast Cancer show a high local control, so this treatment is an real option to Mastectomy in these patients OC-0181 Long-term clinical and cosmetic outcomes of high-dose-rate brachytherapy for early breast cancer F. Arcidiacono 1 , L. Chirico 1 , M. Italiani 1 , P. Anselmo 1 , M. Casale 1 , L. Draghini 1 , F. Trippa 1 , S. Fabiani 1 , M. Basagni 1 , E. Maranzano 1 1 "S.Maria" Hospital, Radiotherapy Oncology Centre, Terni, Italy Purpose or Objective To report long-term clinical and cosmetic outcomes of partial breast irradiation (PBI) with 192 Ir high-dose-rate brachytherapy (HDR-BRT) in early breast cancer patients. Material and Methods From May 2005 to February 2012, 124 patients undergoing conservative surgery for early breast cancer were recruited in a phase II trial of exclusive 192 Ir HDR-BRT. Inclusion criteria were: age >40, PS 0-2, unifocal invasive ductal cancer, intraductal cancer component <25%, negative axillary nodes and tumor size ≤2.5 cm. Treatment schedule was 4 Gy twice a day for 4-5 days, up to a total dose of 32 Gy in 8 fractions with a minimum interval between daily fractions of at least 6 hours. Late toxicity was graded at each follow-up visit according to RTOG/EORTC scoring criteria and cosmetic outcomes according to Harvard criteria and scored as excellent, good, fair and poor. Results Median age was 67 years (range, 42-85). There were 10 (8%) pT1a, 38 (31%) pT1b, 68 (55%) pT1c and 8 (6%) pT2. Estrogenic and progestinic receptors were positive in 113 (91%) and 104 (85%) cases, respectively. 110 (88%) and 15 (12%) patients received adjuvant hormonal therapy and chemotherapy, respectively. Median follow-up was 77 months (range, 8-132). 1 (0,8%) isolated out-field breast relapse occurred 109 months after HDR-BRT. 1 (0,8%) patient developed contralateral breast cancer and another one (0,8%) regional relapse in axillary node. 13 (10,5%) patients reported a second primary cancer. 5- and 10-year overall survival and cancer specific free survival were 95% and 88%, 100% and 98%, respectively. At last follow-up, 114 (92%) patients were alive without disease and 3 (2,5%) with systemic disease. 10 (8%) patients died: 1 (0,8%) for breast cancer, 2 (1,6%) for other cancers and 7 (5%) for other causes. Cosmetic outcomes were excellent in 102 (82%), good in 11 (9%), fair

derived DPs from treatment planning. In addition, the maximal dose to the skin was determined. QC of EMT- based dose distributions were normalized to the corresponding values from treatment planning, so the relative changes are reported. Results Without simulated errors, the maxim um dosimetric deviations to the treatment plan were found on the 2 nd treatment day in median -6.2% for the DNR and -4.3% for the CI of the PTV. For error simulation, 15,107 pairwise swaps of catheters were analyzed. The reconstructed dose distributions resulted in DNR changes form -22.7% to 38.9% (mean: 0.6%, SD: 5.5%) and CI changes from -63.5% to 11.4% (mean: -7.4%, SD: 7.8%). For each shift of single catheters, 2,264 combinations of dose distributions were calculated. Relative dosimetric changes for DNR ranged from -4.1% to 3.5%, from -6.8% to 6.2% and from -8.8% to 8.1% for catheter shifts of 5, 10 and 15 mm, respectively at mean values between 0.0% and -0.3%. The CI for the PTV showed a mean change of -0.3%, -1.3% and -2.8%, respectively. Increased catheter shifts correlated with a higher local dose at the skin (see figures). In addition, each 3D dose distribution was analyzed to identify individual local dose deviations.

Conclusion Statistically, the maximum dose deviation was found on the 2 nd day, what might impact boost treatments with two fractions only. Based on EMT-determined dose calculations adaptive treatment protocols and tests for possible treatment delivery errors should be implemented. Further work is required for the registration method. OC-0180 Prospective study of APBI With Multicatheter Brachytherapy in Local Relapses of Breast Cancer E. Villafranca Iturre 1 , L. Rubi 2 , M. Barrado 1 , A. Sola 1 , P. Navarrete 1 , A. Manterola 1 , M. Dominguez 1 , G. Asin 1 , M. Campo 1 , I. Visus 1 , G. Martinez 1 1 Hospital of Navarra, Radiation Oncology, Pamplona, Spain 2 Hospital Juan Ramon Jimenez, Radiation Oncology, Huelva, Spain