ESTRO 2021 Abstract Book

S760

ESTRO 2021

Scotti 7 , M.E. Rosetto 8 , I. Djan 9 , S. Parisi 10 , G.C. Mattiucci 11 , F. Cellini 5,11 , M. Fiore 12 , P. Bonomo 13 , L. Belgioia 14 , R.M. Niespolo 15 , P. Gabriele 16 , M. Di Marco 3,17 , N. Simoni 18 , R. Mazzarotto 18 , A.G. Morganti 1,3 , S. Cammelli 1,3 1 Radiation Oncology, IRCCS Azienda Ospedaliero-Universitaria di Bologna, Bologna, Italy; 2 Department of Experimental, Diagnostic, and Specialty Medicine (DIMES), Alma Mater Studiorum University of Bologna, Bologna, Italy; 3 Department of Experimental, Diagnostic, and Specialty Medicine (DIMES), Alma Mater Studiorum University of Bologna, Bologna, Italy; 4 Radiation Oncology Unit, Gemelli Molise Hospital – Università Cattolica del Sacro Cuore, Campobasso, Italy; 5 Istituto di Radiologia, Università Cattolica del Sacro Cuore, Rome, Italy; 6 Medical Physics Unit, Gemelli Molise Hospital – Università Cattolica del Sacro Cuore, Campobasso, Italy; 7 Radiotherapy Unit, San Rossore Private Hospital, Pisa, Italy; 8 Radiotherapy Unit, Belcolle Hospital, Viterbo, Italy; 9 Institute of Oncology Vojvodina, Sremska Kamenica, Medical Faculty, University of Novi Sad, Novi Sad, Serbia; 10 Unit of Radiation Therapy, IRCCS “Casa Sollievo della Sofferenza” San Giovanni Rotondo, San Giovanni Rotondo, Italy; 11 Fondazione Policlinico Universitario A. Gemelli, IRCCS, UOC di Radioterapia, Dipartimento di Scienze Radiologiche, Radioterapiche ed Ematologiche, Rome, Italy; 12 Radiation Oncology, Campus Bio-Medico University, Rome, Italy; 13 Radiation Oncology, Azienda Ospedaliero- Universitaria Careggi, Florence, Italy; 14 Department of Radiotherapy, Policlinico San Martino, University of Genoa, Genoa, Italy; 15 Radiotherapy Unit, Azienda Ospedaliera San Gerardo, Monza, Italy; 16 Radiation Therapy, Candiolo Cancer Institute - FPO, IRCCS Candiolo, Candiolo, Italy; 17 Medical Oncology Unit, IRCCS Azienda Ospedaliero-Universitaria di Bologna, Bologna, Italy; 18 Department of Radiotherapy, Azienda Ospedaliera Universitaria Integrata, Verona, Italy Purpose or Objective Chemotherapy (CHT) +/- conventionally fractionated chemoradiation (CRT) is the standard treatment option in patients with locally advanced pancreatic cancer (LAPC). In this setting, stereotactic body radiotherapy (SBRT) is another option but evidence on tolerability and efficacy in older patients is lacking. Aim of this study is to compare toxicity and outcomes in patients aged > 65 years treated with SBRT vs conventionally fractionated CRT. Materials and Methods A retrospective multicentric study was performed. One hundred and seventy-four patients aged > 65 years with non-metastatic LAPC and treated with SBRT or conventionally fractionated CRT from 10 different Italian Centres were included. Patients’ characteristics between the two groups were compared using the chi-square test and univariate and multivariate survival analysis were performed using log-rank test and Cox’s- proportional hazard model, respectively. Results Thirty-five patients (median age: 74 years, range: 65-89) were treated with SBRT +/- neoadjuvant or adjuvant CHT with a median total dose of 30.0 Gy (range: 18.0-37.5) and 6.0 Gy (range 5.0-10.0) per fraction and 139 patients (median age: 71 years, range: 65-90) underwent conventional fractionated CRT +/- neoadjuvant or adjuvant CHT with a median total dose of 50.4 Gy (range: 45.0-60.0). Median BED10 was 48.0 Gy and 59.5 Gy, respectively (p<.001). In SBRT group no acute gastrointestinal G3 toxicity was experienced while in the CRT group three gastrointestinal G3 toxicities were registered, with similar G1-2 toxicity in both treatment settings (p=.117). At univariate analysis no statistically significant differences in local control (LC), distant metastasis- free survival (DMFS) and overall survival (OS) between SBRT and conventional CRT were recorded (p=.344, p=.108, p=.916, respectively). One- and 2-year OS in SBRT group were 79.8% and 15.3% respectively, while in the CRT group were 59.7% and 22.0%, respectively. At multivariate analysis, in SBRT cohort administration of biologically equivalent dose > 48.0 Gy impacted positively on LC and OS (p=.004 and p<.001). Conclusion In LAPC patients aged > 65 years SBRT is a safe treatment option with results similar to the ones of conventionally fractionated CRT in terms of toxicity and clinical outcomes. Taking into account the shorter duration, and therefore less discomfort for patients and easier integration with systemic therapies, prospective-comparative studies with a larger sample size are justified. PD-0919 An accurate pretreatment evaluation improves outcomes in LAPC:a single centre review on 104 patients M. Fiore 1 , G.M. Petrianni 1 , P. Trecca 1 , G. D'Ercole 1 , A. Coppola 2 , L.E. Trodella 1 , R. Coppola 2 , S. Ramella 1 1 Campus Bio-Medico University, Radiation Oncology, Rome, Italy; 2 Campus Bio-Medico University, General Surgery, Rome, Italy Purpose or Objective To report clinical outcomes in patients with locally advanced pancreatic cancer (LAPC) selected for chemoradiotherapy (CRT) in a multidisciplinary tumor board. Materials and Methods From 2008 through 2019, 104 patients with LAPC discussed at the weekly multidisciplinary tumor board were accrued in three consecutive prospective studies of CRT with or without induction chemotherapy (IC). In all cases an accurate pre-treatment staging including CT scan, FDG-PET/CT and laparoscopy with peritoneal washing was performed. After IC and approximately 4 weeks after the completion of CRT, a re-evaluation was performed regarding cancer response and resectability with clinical examination, CT scan, FDG-PET/CT scan and laparoscopy. Results 104 patients were evaluated (Figure 1). According to the results of the pre-treatment workup, 31 patients (29.8%) had metastatic disease and were therefore excluded from the protocols. Ten patients experienced disease progression after IC. Sixty-one patients completed CRT. After the combined therapy 12 patients (19.7%) had a disease progression, 49 patients (80.3%) were evaluated for surgery. Of these, 30 patients (61.2%) underwent surgical radical resection. The median follow-up of all patients included in the study was 17.2 months (range, 4.6 to 105.8 months). The median PFS for patients who completed CRT was 13 months. Two-year and three-year LC were 72% and 66%, respectively. Two-year and three-year MFS were 35% and 28%,