ESTRO 2021 Abstract Book

S1116

ESTRO 2021

therapy for 9 -12 months. First, Kaplan-Meier plots depicted BCR rates and univariable and multivariable Cox regression models focused on predictors of BCR. Second, univariable and multivariable Cox regression models were refitted after propensity score (PS) matching. Results Overall, 133 (60.4%) vs. 87 (39.6%) patients were treated with aRT vs. noRT/sRT respectively. Specifically, 26 (11.8%) patients initially managed with observation after RARP developed BCR and were subsequently treated with sRT. Median time from RARP to sRT was 40 months (IQR: 17-62). The aRT patients were older (67 vs. 63 yrs, p < 0.001). Higher rates of postoperative pathological ISUP grade group 4-5 pCa were observed in aRT patients (51.2 vs. 25.2 %; p< 0.001). A statistically significant difference was recorded in aRT and noRT/sRT regarding pT stage (5 vs. 14 patients in stage pT2; 43 vs. 40 in stage pT3a and 85 vs. 33 in stage pT3b, p <0.001). Median time to BCR was 62 vs. 38 months in aRT vs. noRT/sRT patients (p=0.001). In multivariable Cox regression models, noRT/sRT patients were associated with higher BCR rates (hazard ratio [HR]: 3.27, p < 0.001), relative to aRT group. After PS matching (ratio 1:1; aRT = 57 vs. noRT/ sRT= 57) a 5-year BCR rate significant difference was observed (respectively, 40.4 (aRT) vs. 76.4% (noRT/sRT); p < 0.01). Conclusion Adjuvant radiotherapy should be considered in treatment of pN1 patients. Specifically, patients managed with observation/sRT experienced BCR approximately two years before their aRT counterparts. PO-1360 Are the practices of Radiation oncologists harmonious for hormone therapy in prostate cancer? N. Fourati 1 , W. Mnejja 1 , M. Frikha 1 , F. Dhouib 1 , M. Kallel 1 , W. Siala 1 , J. Daoud 1 1 Faculty of medecine University of Sfax, Radiotherapy Department CHU Habib Bourguiba Sfax Tunisia, Sfax, Tunisia Purpose or Objective The purpose of this study was to describe radiation oncologists’ (RO) practices for hormone therapy (HT) in intermediate risk (IR), high risk (HR) and locally advanced (LA) prostate cancer. Materials and Methods An online survey with 13 questions was sent to all RO (a total of 61). The participants were invited to anonymously answer questions regarding 1) indications of HT 2) the sequence of radiotherapy (RT) and HT association 3) optimal duration of treatment. The questions focused on patients treated with a combination of RT and HT for IR (4 questions), HR (5 questions) and LA (4 questions) prostate cancer. Agreement among participants was considered strong if it was greater than 80 per cent and moderate if it was between 50 and 80 per cent. Results A total of 25 RO completed the survey with a response rate of 41%. For IR prostate cancer , a strong agreement (88%) was found for the indication of HT in association with dose escalation RT (>74 Gy). A total agreement (100%) was found for the duration of 6 months. For optimal treatment sequence the agreement was moderate for neo-adjuvant HT and then concomitant with radiotherapy (60%). Ten participants (40%) indicate to add another injection of HT if the 2 scheduled injections were administered before starting the RT. For HR prostate cancer , a strong agreement (92%) was found for the indication of HT in association with dose escalation RT (>74 Gy). For the optimal duration of HT, the agreement was moderate: duration of 24 months, 36 months and 18 months was preferred by 56%, 36% and 8% of participants respectively. For the particular case of T2cN0M0 , PSA<20 ng/ml and Gleason < 8 the agreement was also moderate: 64% for short-term HT and 36% for long-term HT. For the optimal sequence of treatment, a high agreement was found for neoadjuvant and then concomitant and adjuvant HT (80%). For the optimal duration of this neoadjuvant HT, moderate agreement was found for 3-6 months duration. For LA prostate cancer total agreement (100%) was found for the indication of combined HT and RT treatment. For the optimal duration of treatment, the agreement was moderate: 52% for 24 months and 44% 36 months. For the optimal sequence, a total agreement was found for neoadjuvant HT. However, only 52% did not recommend an evaluation before starting RT. Conclusion The results of our study show that practices of RO are not always harmonious. Indeed, a strong agreement was found only in 6 questions (46%). these results underline the importance of drafting national recommendations which could help harmonize practices. PO-1361 Patterns of care for intermediate-risk prostate cancer – results from an online survey V. Mareco 1 , M.C.D. Silva 1 , A.N. Abrunhosa-Branquinho 1 , J. Pisco 1 , S. Saraiva 1 , M.F.D. Pina 1 1 Centro Hospitalar Universitário Lisboa Norte, EPE, Serviço de Radioterapia, Lisbon, Portugal Purpose or Objective There is an ongoing discussion about the effect of elective whole pelvic radiotherapy (WPRT) in prostate cancer (PCa). WPRT might prevent the metastatic spread of cancer cells through lymphatic drainages, but its use is uncertain in addition to dose-escalated prostate radiotherapy (RT) and in terms of progression-free survival. Moreover, total doses and fractionation seem to differ between RT Departments. A sequential two phase process, initial and boost RT, is a common practice, but a recent intensity-modulated RT simultaneous integrated boost strategy that irradiates prostate via hypofractionation is being increasingly adopted. Our objective is to describe the practices reported by different Departments. Materials and Methods An online survey (by Google Forms) consisting of 7 questions about how to treat a clinical case vignette ( vide figure) was shared through groups of Radiation Oncologists (RO) on social networks to collect data regarding target volume selection and fractionation schemes, from 11 May 2020, with analysis performed after data lock on 8 March 2021. The vignette was a 66-year patient with an initial prostate-specific antigen level of