ESTRO 2023 - Abstract Book

S32

Saturday 13 May

ESTRO 2023

Data of 1031 SRTs in 479 patients were analyzed. Primary cancer was melanoma (36%), NSCLC (37%), RCC (8%) and breast cancer (6%). ECOG-PS was 0-1 in 92% of patients. SRT of brain or extracranial metastases was performed in 273 and 208 patients, respectively. A median of 1 (range 1-15) lesions was treated with SRT, which was combined with immune checkpoint inhibitors (ICI) (61.4%), TT (29.4%) or antibodies (9%). TT/IT was mostly started before SRT in 69%, with a median of 112 days (range 1-2751) and was interrupted during SRT in 15% of patients, with a median break of 6 (range 1-56) days. Median OS was 24mo (95% CI 20-27mo), PFS 7mo (95% CI 5-9mo) and TTD 22mo (95% CI 19-25mo). 72% of progressing patients received repeat-SRT, radiotherapy or surgery instead of a systemic therapy switch. Severe acute and late SRT-related toxicity occurred in 6.6% and 6.9% of patients, respectively. These included n=5 G5 toxicities, which were all observed in the BRAF/MEKi and aPD-(L)1 group. Most acute severe toxicity was observed in the aPD-(L)1 (6%), aPD-1/aCTLA-4 (9%) and BRAF/MEKi (15%) group, severe late toxicity was most frequently observed in patients receiving concurrent aPD-(L)1 (4.8%), and aEGFR/EGFRi (21%). Overall, there was no significantly increased severe toxicity, whether TT/IT was continued or interrupted during SRT (p=0.098). Conclusion This prospectively collected real-world data observed that metastases-directed SRT combined with TT/IT had only short- term effect on the prevention of further distant progression, but enabled a systemic therapy discontinuation for almost one year. Severe SRT-induced toxicity was limited in both intracranial- and extracranial disease. The development of severe toxicity was not significantly influenced by continuation of these targeted agents during SRT. PD-0065 Short course palliative radiotherapy in advanced solid tumors: a pooled analysis (SHARON PROJECT) C.M. Donati 1 , G. Macchia 2 , C. Malizia 3 , G. Siepe 4 , A. Zamagni 1 , F. Cellini 5 , M. Buwenge 6 , S. Cilla 7 , S. Cammelli 8 , S. Rizzo 9 , L. Caravatta 10 , T. Wondemagegnhu 11 , A.F.M.K. Uddin 12 , B.T. Deressa 13 , M.A. Sumon 11 , L. Strigari 14 , E. Lodi Rizzini 3 , A. Bazzocchi 15 , A.G. Morganti 8 , F. Deodato 2 , E. Farina 16 1 Radiation Oncology, Department of Experimental, Diagnostic and Specialty Medicine-DIMES, Alma Mater Studiorum University of Bologna, IRCCS Azienda Ospedaliero-Universitaria di Bologna, Bologna, Italy; 2 Radiotherapy Unit, Gemelli Molise Hospital, Catholic University of Sacred Heart, Campobasso, Italy; 3 Nuclear Medicine, IRCCS Azienda Ospedaliero- Universitaria di Bologna, Bologna, Italy; 4 Radiation Oncology, IRCCS Azienda Ospedaliero-Universitaria di Bologna, Bologna, Italy; 5 Fondazione Policlinico Universitario "A. Gemelli" IRCCS, Dipartimento di Diagnostica per Immagini, Radioterapia Oncologica ed Ematologia, Università Cattolica del Sacro Cuore, Dipartimento Universitario Diagnostica per immagini, Radioterapia Oncologica ed Ematologia, Rome, Italy, Istituto di Radiologia, Università Cattolica del Sacro Cuore, Roma, Italy; 6 Radiation Oncology, Department of Experimental, Diagnostic and Specialty Medicine, Alma Mater Studiorum University of Bologna, Bologna, Italy; 7 Medical Physics Unit, Gemelli Molise Hospital-Università Cattolica del Sacro Cuore, Campobasso, Italy; 8 Radiation Oncology, Department of Experimental, Diagnostic and Specialty Medicine- DIMES, Alma Mater Studiorum University of Bologna, IRCCS Azienda Ospedaliero-Universitaria di Bologna, Bologna, Italy; 9 Service of Radiology, Imaging Institute of Southern Switzerland, Ente Ospedaliero Cantonale (EOC), Lugano, Switzerland; 10 Radioterapia, Università degli Studi G. D’Annunzio, Chieti, Italy; 11 Department of Radiation Oncology, Black Lion Hospital, Addis Ababa, Ethiopia; 12 Department of Radiation Oncology, United Hospital Limited, Dhaka, Bangladesh; 13 Department of Radiation Oncology, Black Lion Hospital , Addis Ababa, Ethiopia; 14 Medical Physics Unit, IRCCS Azienda Ospedaliero-Universitaria di Bologna, Bologna, Italy; 15 Diagnostic and Interventional Radiology, IRCCS Istituto Ortopedico Rizzoli, Bologna, Italy; 16 Radiotherapy Unit, Azienda Ospedaliero-Universitaria di Ferrara, Ferrara, Italy Purpose or Objective Previous trials showed the tolerability and efficacy of a palliative radiotherapy (RT) regimen (SHARON) based on the 4 fractions delivered in 2 days in different oncological settings. In order to identify possible predictors of symptomatic response, the purpose of this study is to perform a pooled analysis of previous trials. Materials and Methods We analyzed the impact on symptomatic response of the following parameters: tumor site, histological type, performance status (ECOG), dominant symptom, and RT dose using the chi-square test. Results One-hundred-eighty patients were analyzed. Median RT dose was 20 Gy (range: 14-20 Gy). The overall response rate was 88.8% (95%CI: 83.3%-92.7%) while pre- and post-treatment mean VAS was 5.3 and 2.5, respectively (p < .001). The overall response rate of pain, dyspnea, bleeding, dysphagia, and other symptoms was 86.2%, 90.9%, 100%, 87.5%, and 100%, respectively. Comparing the symptomatic effect based on the analyzed parameters no significant differences were recorded. However, patients with locally advanced disease showed a higher rate of symptomatic responses than metastatic ones (97.3% versus 83.0%; p = .021). Finally, the complete pain response rate was more than double in patients with mild to moderate (VAS: 4-7) compared to those with severe (VAS > 7) pain (36.0% versus 14.3%; p = .028).

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