ESTRO 38 Abstract book

S773 ESTRO 38

e Cura “Giovanni Paolo II”, Radiotherapy Unit, Campobasso, Italy ; 3 Fondazione di Ricerca e Cura “Giovanni Paolo II”, Medical Phisyc Unit, Campobasso, Italy ; 4 Radiosurgery Center Malzoni, Radiosurgery Center, Agropoli, Italy ; 5 Ospedale Belcolle, Radiotherapy Unit, Viterbo, Italy ; 6 Medical Faculty- University of Novi Sad, Institute of Oncology Vojvodina- Sremska Kamenica, Novi Sad, Serbia ; 7 Ospedale Casa Sollievo della Sofferenza San Giovanni Rotondo, Radiotherapy Unit, San Giovanni Rotondo- Foggia, Italy ; 8 Policlinico Universitario “A. Gemelli”- Università Cattolica del Sacro Cuore, Department of Radiotherapy, Rome, Italy ; 9 Università Campus Biomedico, Department of Radiotherapy, Rome, Italy ; 10 Azienda Ospedaliero Universitaria Careggi AOUC- Università di Firenze, Department of Radiotherapy, Florence, Italy ; 11 IRCCS AOU San Martino– IST, Department of Radiotherapy, Genova, Italy ; 12 Azienda Ospedaliera San Gerardo, Radiotherapy Unit, Monza Mi, Italy ; 13 Fondazione del Piemonte per l'Oncologia FPO- IRCCS Candiolo, Department of Radiotherapy, Torino, Italy ; 14 University Hospital, Radiotherapy Unit, Verona, Italy Purpose or Objective Locally advanced pancreatic cancer (LAPC) presents an intermediate prognosis between resectable and metastatic patients, with a median overall survival (OS) ranging from 9 to 13 months. A standard treatment approach is lacking with large variation between different institutions. We performed a real-life study retrospectively reviewing the experience of 6 different centers treating LAPC with stereotactic body radiotherapy (SBRT). Material and Methods We included 56 pts with LAPC, undergoing SBRT +/- chemotherapy (CT) with multiagent CT regimens. Exclusion criteria were metastatic disease and radical surgical treatment. Only palliative surgery was allowed. Median total dose, median dose/fraction, and median equivalent dose (EQD 2 [α/β 10Gy ]) for SBRT were 30 Gy (range: 18-45), 6 Gy (range: 4-10), and 40 Gy (range: 23- 65) respectively. Toxicity was evaluated by CTCAE version 5.0 scale. Overall survival, local control (LC), and disease metastasis-free survival (DMFS) were estimated and compared by Kaplan-Meier and log-rank methods, respectively. Results We included 56 pts in this analysis (M/F: 31/25; median age: 68, range: 36-89). Median, 6 months, 1-year, and 2- year OS were: 19.0 months, 92.9%, 81.9%, and 27.1%, respectively. Six months, 1-year, and 2-year LC were: 92.5%, 76.3%, and 55.4% (median LC was not reached), respectively. Median, 6 months, 1-year, and 2-year DMFS were: 15.0 months (range 12.0-17.9), 87.3%, 59.5%, and 26.0%, respectively. A better prognosis was recorded in pts treated with both neoadjuvant (median OS: 15.0 vs 24.0 months, p=0.002) and adjuvant CT (median OS: 15.0 vs 29.0 months, p=0.017). Patients treated with a total SBRT dose ≥30 Gy (p=0.030), with a fractionation dose ≥ 6 Gy (p= 0.014), and with a computed EQD 2 [α/β 10Gy ] ≥40 Gy (p= 0.007) had a better OS. Total dose (p= 0.024) and EQD 2 [α/β 10Gy ] (p= 0.024) were significantly associated to higher local control. Gastrointestinal (GI) acute toxicity rates were as follows: G1: 24.4%, G2: 2.3%, G3: 0.0%. Only one case of G3 GI late toxicity (2.5%) was recorded.

Conclusion SBRT +/- CT resulted tolerable and effective in this “real- life” retrospective analysis. Further prospective studies are needed to define optimal radiation schedules and integration modalities with systemic therapies. EP-1424 SBRT vs chemoradiation: a case-control study (PAULA-2) A. Arcelli 1 , F. Bertini 1 , A.G. Morganti 1 , A. Guido 1 , F. Deodato 2 , S. Cilla 3 , F. Dalla Torre 2 , V. Scotti 4 , M.E. Rosetto 5 , I. Djan 6 , S. Parisi 7 , G.C. Mattiucci 8 , M. Fiore 9 , P. Bonomo 10 , A. Bacigalupo 11 , R.M. Niespolo 12 , P. Gabriele 13 , N. Simoni 14 , R. Mazzarotto 14 , G. Macchia 2 1 Radiation Oncology Center- University of Bologna, Department of Experimental- Diagnostic and Specialty Medicine - DIMES, Bologna, Italy ; 2 Fondazione di Ricerca e Cura “Giovanni Paolo II”, Radiotherapy Unit, Campobasso, Italy ; 3 Fondazione di Ricerca e Cura “Giovanni Paolo II”, Medical Physic Unit, Campobasso, Italy ; 4 Radiosurgery Center Malzoni, Radiosurgery Center, Agropoli, Italy ; 5 Ospedale Belcolle, Radiotherapy Unit, Viterbo, Italy ; 6 Medical Faculty- University of Novi Sad, Institute of Oncology Vojvodina- Sremska Kamenica, Novi Sad, Serbia ; 7 Ospedale Casa Sollievo della Sofferenza San Giovanni Rotondo, Radiotherapy Unit-, San Giovanni Rotondo FG, Italy ; 8 Policlinico Universitario “A. Gemelli”- Università Cattolica del Sacro Cuore, Department of Radiotherapy, Rome, Italy ; 9 Università Campus Biomedico, Department of Radiotherapy, Rome, Italy ; 10 Azienda Ospedaliero Universitaria Careggi AOUC- Università di Firenze, Department of Radiotherapy, Firenze, Italy ; 11 IRCCS AOU San Martino– IST, Department of Radiotherapy, Genova, Italy ; 12 Azienda Ospedaliera San Gerardo, Radiotherapy Unit-, Monza MI, Italy ; 13 Fondazione del Piemonte per l'Oncologia FPO- IRCCS Candiolo, Department of Radiotherapy, Torino, Italy ; 14 University Hospital, Radiotherapy Unit, Verona, Italy Purpose or Objective Treatment of locally advanced pancreatic cancer (LAPC) is controversial. SBRT is an emerging radiotherapy technique able to achieve high local control rates. We performed a case control study comparing outcome in terms of local control (LC), disease metastases-free survival (DMFS), and overall survival (OS) between two cohorts of patients treated with chemoradiation (CRT) +/- chemotherapy (CT) or SBRT +/- CT. Material and Methods Patients (pts) treated with CRT +/- neoadjuvant CT, +/- adjuvant CT (control group: CG) were matched to pts treated with SBRT +/- neoadjuvant CT, +/- adjuvant CT (case group: SG) based on age (≤/> 65years), tumor diameter (<3.0 cm; 3.0-3,9 cm; and ≥ 4.0 cm), clinical T stage, clinical N stage, neoadjuvant CT, adjuvant CT. Matching was performed without knowledge of outcomes. Median dose in pts treated with SBRT was 30.0 Gy (range: 18.0-35.0) and median dose in pts treated with EBRT was 50.4 Gy (range: 18.0-63.0). Survival curves were assessed