Abstract Book

S713

ESTRO 37

Conclusion Our experience showed low rates of acute and early late complications. Longer follow up time is strongly needed. PMRT seems to be feasible and safe after mastectomy with immediate subcutaneous E/I reconstruction. EP-1300 Efectiveness of once-weekly hypofractionated irradiation in 486 elderly breast cancer patients. X. Sanz 1 , N. Rodríguez 1 , P. Foro 1 , A. Reig 1 , I. Membrive 1 , M. Zhao 2 , P. Perez 1 , L. Montezuma 1 , R. Granado 1 , M. Algara 1 1 Parc de Salut Mar, Radiation Oncology, Barcelona, Spain 2 Universitat Autonoma de Barcelona, Medicine, Barcelona, Spain Purpose or Objective Radiation therapy plays a key role in the multi- disciplinary treatment of breast cancer. The usual schedule requires patients to come to the radiotherapy center f or daily treatment, however, elderly patients with qassociated diseases that alter the general condition do not tolerate long periods of daily irradiation. The objective of this study is to analyze the results of weekly hypo-fractionated treatment in these patients. Material and Methods Between 1996 and 2016, we have included elderly patients carrying several concomitant pathology or socio- familial problems in which it is not feasible to propose conventional treatment. Patients with I-II stages underwent conservative treatment and patients with stage III submitted to mastectomy, followed by adjuvant weekly hypo-fractionated irradiation.The irradiation schedule consisted in 6 fractions of 6.25 or 5 Gy per fraction once a week up to a total dose of 37.5 Gy o 30 Gy, by means of a Cobalt-60 unit and mainly with photons 6 MV of a linear accelerator and conformal 3D planning. A boost of 1 or 2 additional sessions at the same fractionation was administered in case of involvement of the surgical margins. Node areas were treated in case of positive nodes. All patients were evaluated weekly for treatment tolerance and underwent control of acute local toxicity according to the RTOG scale indicating supportive treatment when necessary. Patients were followed periodically after a month, 3 or 6 months and subsequently at least once at a year evaluating chronic toxicity, local and systemic control. Results An amount of 486 consecutive patients have been evaluated. The patients underwent conservative breast surgery in 78.6% of cases, total mastectomy in 20%, biopsy alone in 1.4%. Patients received once-weekly irradiation of 6.25 Gy in 90.7% of the series and 5 Gy in the remaining 9.3% of patients. They received 6 weekly fractions in 80.7% of and a boost was delivered to the tumor bed in 17.5% (1-2 additional sessions). In 1.8% of cases the treatment was uncompleted due to medical conditions. After a median follow-up of 51 months, the overall survival according to the Kaplan-Meier method after 5-year was 74.2% ± 2.3%, the specific survival was 90% ± 1.6%, the local relapse free survival was 96.5% ± 1% and metastasis-free survival was 90% ± 1.6%, Regarding toxicity, 75.6% of the patients had grade I-III acute dermatitis and 30.6% had mild or moderate chronic fibrosis, mainly asymptomatic. Conclusion Due to old patient age in this series the mortality is mainly produced by other diseases than breast cancer, leading to a high specific survival and local control, This weekly schedule leads to a good acute tolerance, the chronic toxicity is mild, allows better compliance of treatment and increases the quality of life in older patients with breast cancer.

subcutaneous E/I reconstruction. Among them, 43 patients received PMRT on the chest wall and 3-4 axillary levels (50 Gy in 25 fractions). Capsular contracture, rippling, implant’s profile visibility, implant borders tangibility at smooth touch, and aesthetic result evaluation was conducted by two different physicians at the same time, giving a single agreed score for every item. Radiation treatment tolerance was assessed using the acute radiation morbidity scoring criteria and late radiation morbidity scoring scheme from the Radiation Therapy Oncology Group (RTOG) and the European Organization for Research and Treatment of Cancer (EORTC). Results Main patients and treatments characteristics are summarized in Table 1. Acute surgical complications were observed in five cases (11.6%): four wound skin infections, and one hematoma. Among them, two patients required E/I substitution. At a median follow up time of 30 months (mean 38.4; range 18 - 60), two cases of late complications after PMRT have been observed (4.6%), both showing capsule contraction. Concerning early late radiation-related side effects, we observed two skin fibrosis (4.6%), one hyperpigmentation (2.3%), one telangiectasia (2.3%); overall four cases of any breast skin toxicity were recorded (9.3%). Five patients developed distant metastases (11.6%), while no local relapses were observed.