ESTRO 2023 - Abstract Book

S1208

Digital Posters

ESTRO 2023

PO-1491 Profiling PCa patients with BCR in the era of early imaging detection: an AIRO-URO group study

G. Marvaso 1,2 , F. Matrone 3 , A. Magli 4 , G. Francolini 5 , R. Villa 6,2 , F. Mastroleo 6 , C. Franzese 7 , L. Nicosia 8 , F. Pasqualetti 9 , L.E. Trodella 10 , A. Vinciguerra 11 , S. Barra 12 , G. Timon 13 , M. Augugliaro 14 , M. Zaffaroni 15 , G. Corrao 15 , M.G. Vincini 6 , M. Scorsetti 15 , B.A. Jereczek-Fossa 6,16 , S. Arcangeli 17 , L. Triggiani 18 1 IEO, European Institute of Oncology, IRCCS, Division of Radiation oncology, Milan, Italy; 2 University of Milan, Department of Oncology and Hemato-oncology, Milan, Italy; 3 Centro di Riferimento Oncologico di Aviano CRO-IRCCS, Department of Radiation Oncology, Aviano, Italy; 4 Udine General Hospital, Department of Radiation Oncology, Udine, Italy; 5 A.O.U. Careggi, University of Florence, Radiation Oncology, Firenze, Italy; 6 IEO, European Institute of Oncology, IRCCS, Division of Radiation Oncology, Milan, Italy; 7 Humanitas Clinical and Research Center - IRCCS, Department of Radiotherapy and Radiosurgery, Milan, Italy; 8 IEO, European Institute of Oncology, IRCCS, Breast Imaging Division, Radiology Department, Milan, Italy; 9 Azienda Ospedaliera Universitaria Pisana, University of Pisa, Department of Radiation Oncology, Pisa, Italy; 10 Campus Bio-Medico University, Radiation Oncology, Rome, Italy; 11 "SS Annunziata" Hospital, "G. D'Annunzio" University, Via dei Vestini, Department of Radiation Oncology, Chieti, Italy; 12 Ospedale Policlinico San Martino, Pediatric Radiotherapy and Special Techniques Unit, Genova, Italy; 13 Azienda USL-IRCCS di Reggio Emilia, Radiation Oncology Unit, Reggio Emilia, Italy; 14 Azienda USL-IRCCS di Reggio Emilia, Radiation Therapy Unit, Reggio Emilia, Italy; 15 IEO, European Institute of Oncology, IRCCS, Division of Radiation Oncology, Milan, Italy; 16 University of Milan, Department of Oncology and Hemato Oncology, Milan, Italy; 17 School of Medicine and Surgery, University of Milan Bicocca, Department of Radiation Oncology, Milan, Italy; 18 ASST Spedali Civili di Brescia, University of Brescia, Radiation Oncology Department, Brescia, Italy Purpose or Objective Although radical prostatectomy represents a curative treatment, 44% of patients experience BCR at least 6 months after surgery. While in low-risk patients, the interval between surgery and BCR does not influence mortality, in patients with unfavorable disease characteristics, early disease recurrence increases mortality risk. Aim of the present study is to create a predictive model capable of identifying the category of patients most at risk of local or distant metastasis to undergo early imaging investigations. Materials and Methods Data have been acquired from Italian centers joining the AIRO-URO initiative. Patients who underwent RP and salvage RT after experiencing BCR have been considered for study inclusion. Descriptive and frequency analysis has been performed and mean time to event has been calculated for variables involving timespans. Disease progression after salvage radiotherapy has been considered as event of interest in time-to-event analysis. Multivariate Cox Regression model with multi-block enter approach has been adopted, chi-square test for log likelihoods significant difference was used in the rounds to assess increase in model performance. Covariates were defined significative when p < 0.05 and HR not encompassing 1. Results A total of 580 patients (median age 64.7 y) with a median follow-up of 4.5 y (range 0.2-15.9) were included in the analysis. IMRT/VMAT accounted for 90.7% of all the treatment modalities. Biochemical progression-free survival rate < 12 months was 92%, at 1-year 83%, and at 2-years 75%. In the Multivariate Cox Regression model, 232 of 580 (39.9%) biochemical disease progression events have been considered eligible for the analysis. Median biochemical progression-free survival time resulted 2.1 y. Site of progression was available for 171 patients out of the reported 232 events. Of them, pelvic and distant progression occurred in 55% and 45% of the patients. Survival Cox Regression plot can be seen in Fig1 . The covariates found significantly associated with a higher risk of biochemical disease progression were: PSA higher or equal to 0.5 ng/ml at the biochemical relapse (HR 1.422, CI 95% 1.036-1.952, p < 0.029) and less than 12 months from surgery to biochemical relapse (HR 1.718, CI 95% 1.299-2.271, p < .001). Pelvic irradiation during salvage radiotherapy (HR 0.670, CI 95% 0.469-0.958, p < .028) was significantly associated with a lower risk of recurrence. Figure 1