ESTRO 38 Abstract book

S722 ESTRO 38

Data from 20 patients and a total of 21 RBC were analyzed. Patients were treated with a median re-RT dose of 50.4 Gy (range, 39.6-60.4 Gy) and a median of 11 HT fractions (range, 2-23). Median time between RT und re-RT+HT was 66.2 months (range, 9.2-436.4). Re-RT+HT was well tolerated. Three patients experienced grade (G) 3 acute skin toxicity. No ≥ G3 late toxicity was observed. With a median follow up of 24.7 months (range, 5.8-56.5) two local relapses occurred. Ten patients experienced regional and/or distant disease progression. Five patients died, four of them from breast cancer. PFS was found to be favorable in patients treated with re-RT+HT for the first recurrence and with total doses of 60 Gy. A trend towards better CSS was found in patients with negative or close resection margins and after doses of 60 Gy.

competing risks we used Fine-Gray models to assess tumor-specific survival. Models were adjusted for age and grading. Results The application of radiotherapy in patients with hormone therapy increased from 71.4% in years before 2005 to 83.3% thereafter. In women aged 70 to 74 years 87.70 received radiotherapy. The figure decreased to 84.4% for patients between 75 and 79 years, and 57.6% in patients with 80 years or older. Considering all patients, only 2.6% were recorded to have died from breast cancer, while of all deaths breast cancer was the leading cause in 17.1%. Median survival was 51 months (95% CI: 45-55 months) for the radiotherapy group and 42 month for the hormone therapy (95% CI: 34-50 months) Patients treated with additional radiotherapy had a better survival prospect when compared to women who received only hormone therapy (HR= 0.62, 95% CI: 0.52-0.73). Survival analyses revealed a benefit for patients with additional radiotherapy when compared patients with only hormone therapy (HR=0.41, 95% CI: 0.2-0.81) in terms of breast cancer-specific survival. Likewise, non-breast cancer-specific survival was more favorable in the radiotherapy group (HR=0.61, 95% CI: 0.44-0.86). Conclusion Radiotherapy is widely applied in elderly breast cancer patients above an age of 70. However, due to the few deaths from breast cancer the benefit in terms cancer- specific survival remains unclear when population-based data are considered. EP-1317 Hyperthermic chest wall re-irradiation in recurrent breast cancer: a prospective observational study C. De Colle 1 , N. Weidner 1 , V. Heinrich 1 , S. Brucker 2 , M. Hahn 2 , K. MacMillan 1 , U. Lamprecht 1 , S. Gaupp 1 , O. Voigt 1 , D. Zips 1,3 1 Eberhard Karls University Tübingen, Radiooncology, Tübingen, Germany ; 2 Eberhard Karls University Tübingen, Department of women's health, Tübingen, Germany ; 3 German Cancer Reaserch Center DKFZ and German Cancer Consortium DKTK partner site Tuebingen, Radiooncology, Tuebingen, Germany Purpose or Objective Surgical resection is the standard therapy for recurrent breast cancer (RBC). To increase local control (LC), especially after microscopically (R1) or macroscopically (R2) positive or close resection margins, re-irradiation is indicated. In these cases, radiotherapy (RT) must be carefully evaluated because re-RT might cause relevant toxicities. RT combined with hyperthermia (HT) as adjuvant treatment for RBC has been shown to improve LC compared to RT alone through a radiosensitizing effect. Despite the fact of level I evidence for re-RT+ HT, which was generated in the 1990s, it remains important to prospectively investigate this treatment because diagnosis and treatment of primary and RBC have continuously improved over the last 20 years. Material and Methods Within the prospective registry HT03, patients with resected RBC (R1, R2 or close margins) and previously irradiated were included. Patients were treated with involved field RT to the chest wall limited to the region of recurrence with 50-50.4 Gy in 25-28 fractions followed by a boost up to a total dose of 60-60.4 Gy to the R1/R2 region. Concurrent superficial HT was performed twice per week with a therapeutic temperature of 40°- 42°C applied for 75 minutes. Primary endpoint was LC. In addition, acute and late toxicity according to CTCAE and RTOG criteria, overall survival (OS), cancer-specific survival (CSS) and progression-free survival (PFS) were evaluated. Results

Conclusion Re-RT+HT for RBC is well tolerated and provides good LC. Re-RT+HT seems to be more effective when applied at the time of the first relapse and after doses of at least 60 Gy. The registry will be continued for validation in a larger cohort and with longer follow up. EP-1318 Hypofractionated radiotherapy for breast cancer in elderly patients: 10 or 5 fractions? E. Bonzano 1 , G. Polizzi 1 , M. Guenzi 1 , R. Corvò 1 1 IRCCS Policlinico San Martino and University, Department of Radiation Oncology, Genoa, Italy Purpose or Objective The aim of this study, was to compare 5 fractions(fx) one weekly hypofractionated Adjuvant Radiotherapy (RT) versus 10 fx four weekly hypofractionation in elderly patients(pts) affected by early breast cancer and to report clinical outcomes: skin toxicity profile, aesthetic result and treatment feasibility. Material and Methods This retrospective study was conducted on 96 pts, aged over 70 years old (median age 79 y.o., range 72-95) with no severe comorbidities. From October 2016 to June 2017, pts underwent adjuvant radiotherapy, with two different hypofractionated schedules. The first group (groupA) underwent 28,5 Gray(Gy)/5fractions/1 fraction weekly plus/minus a 2.5 Gy Simultaneous Boost (SIB) on tumor bed in “high risk” cases, the second one (groupB) 35Gy/10 fractions/4 times a week with a concomitant boost of 3 or 4 Gy once a week, according to risk factors. Pts in both groups were pT1-2N0-1a, with different biologic patterns, laterality and size. Treatment was delivered in supine position, with tangential fields. Conventional 3DCRT constraints for lungs and heart were used; V20=0 for Left Anterior Descending Artery (LADCA) was translated to V12 for the one weekly hypofractionation and to V14 for the four weekly one, according to the radiobiological calculation. Acute skin toxicity and late subcutaneous