ESTRO 2021 Abstract Book

S946

ESTRO 2021

Conclusion FACT-B resulted as a simple and quick questionnaire. RT seems do not affect QoL of BC patients, neither in terms of fractionation regimen or RT-related side effects. Moreover, women having systemic HT experienced a QoL worse than patients treated with only RT. Currently the definition of QoL is not universally accepted; it changed in the course of time, becoming more complex and enriched across several disciplines. The long survival rates and increasing proportions of cured patients require dedicated strategies to manage long-term sequelae of BC treatments, with particular attention to QoL. The follow-up up to 30 months is currently ongoing to validate long-term implications of treatments on QoL. PO-1138 Preoperative radiation therapy in breast cancer: preliminary results from ROCK trial (NCT03520894) V. Di Cataldo 1 , G. Francolini 2 , L. Visani 1 , C. Becherini 2 , E. Scoccimarro 3 , L. Masi 1 , R. Doro 1 , G. Salvatore 4 , S. Bianchi 5 , V. Vezzosi 6 , E. Lemmi 6 , J. Nori 7 , L. Sanchez 8 , L. Orzalesi 8 , M. Bernini 8 , M. Loi 2 , I. Desideri 4 , M. Mangoni 4 , I. Meattini 4 , L. Livi 4 1 IFCA, Cyberknife, Florence, Italy; 2 Azienda Ospedaliero-Universitaria Careggi, Radiation Oncology Unit, Oncology Department, Florence, Italy; 3 University of Florence, Department of Experimental and Clinical Biomedical Sciences Mario Serio, Florence, Italy; 4 University of Florence, Department of Biomedical, Experimental and Clinical Sciences "Mario Serio", Florence, Italy; 5 Azienda Ospedaliero-Universitaria Careggi, Division of Pathological Anatomy, Florence, Italy; 6 Azienda Ospedaliero-Universitaria Careggi, Division of Pathological Anatomy, Florence, Italy; 7 Azienda Ospedaliero-Universitaria Careggi, Diagnostic Senology Unit, Florence, Italy; 8 Azienda Ospedaliero-Universitaria Careggi, Breast Surgery Unit, Florence, Italy Purpose or Objective Preoperative radiation therapy in early breast cancer (BC) may have potential advantage if compared with standard breast conserving surgery (BCS) followed by postoperative radiation. Our institution is currently conducting an exploratory study enrolling early BC patients undergoing preoperative robotic stereotactic radiosurgery (prRS) (NCT03520894-ROCK trial). Materials and Methods Womens age 50 or older, with histologically proven invasive BC, positive hormonal receptors, HER-2 negative, without lymphovascular invasion, and tumour size up to 25 mm, negative clinical nodal status, eligible for BCS were enrolled. Fiducial markers were introducted in peri/intralesional position (3-5 markers) one week before planning CT. Magnetic resonance imaging (MRI) was used in conjunction with standard computed tomography (CT)-based planning to identify contrast enhancing tumor. Patients received 21 Gy in single fraction prRS followed by definitive surgery two weeks later. Objects of this preliminary analysis were incidence of acute skin toxicity after treatment according to EORTC/RTOG scale and efficacy. Results Of 49 patients screened on mammography findings, 18 were elegible for histology. Of those, 7 were excluded at the time of MRI due to multifocal disease and 12 patients were succesfully treated. All required dosimetric parameters were met in all patients, as were normal tissue constraints. The median follow-up was 18 months (range 6-29.8). All treated patients underwent to BCS within 14 day from prRS without any delay or complication. No patients showed erythema or pain at the time of BCS and no wound dehiscence was observed. No patients experienced acute skin toxicity of grade 2 or higher, only 1 patients had a grade 1 erythema at the 1 month postoperative visit. According to Chevallier’s classification 1 patient had a pathological complete response (pCR). Conclusion Preliminary results from ROCK trials showed that prRS in BC is a feasible technique of implementing single dose preoperative radiation therapy. PrRS is well tolerated with a tolerable safety profile and a promising rate of response. This new approach in breast cancer management is currently based on limited data but should be further investigated to corroborate these findings. Considering drop out rate if compared to overall cohort of screened patients, selection criteria and multidisciplinary collaboration represent a critical issue in this scenario.

PO-1139 Skin toxicity in 1325 breast cancer patients treated with hypofractionated RT without boost