ESTRO 2023 - Abstract Book

S1206

Digital Posters

ESTRO 2023

Purpose or Objective Biochemical recurrence of prostate cancer after radical prostatectomy are recorded in approximately 15 to 30% of cases. Treatment options are represented by salvage radiotherapy (SRT), hormonal therapy, or observation with PSA level monitoring. In patients eligible for SRT, current guidelines recommend PSMA PET to exclude distant metastases. An observational study of our centre (ICAROS) was carried out to evaluate a possible role of MRI before SRT. Aim of this report was to describe the preliminary results. Materials and Methods Over a 4-year period, all patients eligible to SRT without contraindications to MRI underwent clinical and instrumental examination including pelvic multi-parametric MRI with endorectal coil, possibly associated with choline or PSMA PET. The following data were prospectively collected: PSA at biochemical relapse, PSA doubling time, ISUP score, SRT treatment plan, site and of any macroscopic recurrence, outcome. Results Fifty-eight patients were evaluated in this study. Median age was 64 years (range: 41-78), median PSA level at biochemical recurrence was 0.66 ng/ml (range: 0.12-6.24), and most patients (68.9%) had ISUP 3-5. Pre-SRT MRI was positive for local recurrence in 40/58 patients (68.9%), for pelvic nodal metastases in 1/58 (1.7%), and for pelvic bone metastases in 1/58 (1.7%). The site of local recurrence was as follows: bladder neck 30/42 (71.4%), vesicourethral anastomosis 7/42 (16.7%), rectovesical space 2/42 (4.8%), prostatic fossa 1/42 (2.4%). Twenty-eight patients (66.7%) with positive MRI also underwent choline or PSMA PET. Of these, only 9 patients (21.4%) showed the same uptake at the same sites as evidenced by MRI. Conversely, in 19 patients (45.2%) MRI results did not match the PET result. Conclusion An unexpectedly high rate of macroscopic local relapse was recorded in a cohort of patients with biochemical recurrence after radical prostatectomy and prospectively assessed with MRI. These results challenge current recommendations on the most appropriate imaging exams in this clinical setting. A. Fodor 1 , C. Deantoni 1 , L. Giannini 1 , F. Ferrario 1 , S. Villa 1 , P. Mangili 2 , L. Perna 2 , S. Broggi 2 , I. Dell'Oca 1 , F. Zerbetto 3 , C. Chissotti 1 , M. Midulla 1 , M. Torrisi 1 , B. Longobardi 2 , R. Castriconi 2 , A. Del Vecchio 2 , C. Cozzarini 1 , C. Fiorino 2 , N. Di Muzio 4 1 IRCCS San Raffaele Scientific Institute, Department of Radiation Oncology, Milan, Italy; 2 IRCCS San Raffaele Scientific Institute, Medical Physics, Milan, Italy; 3 IRCSS San Raffaele Scientific Institute, Department of Radiation Oncology, Milan, Italy; 4 IRCCS San Raffaele Scientific Institute & Vita-Salute San Raffaele University, Department of Radiation Oncology, Milan, Italy Purpose or Objective Patients treated for lymph-nodal metastases (LNM) of prostate cancer (PC) are often an inhomogeneous population, including either hormonal-sensitive (HSPC) or castration-resistant patients (CRPC), at the first or second radiation therapy (already treated with adjuvant or salvage radiotherapy, ART/SRT), who could have different prognoses. Here we report long-term outcomes of our cohort of patients treated with salvage extensive–nodal radiotherapy (ENRT) and positron emission tomography (PET)-guided simultaneous integrated boost (SIB) on PET positive LNM, considering these differences. Materials and Methods From 02/2005 to 11/2021, >200 PC patients were treated for LNM with ENRT at a median total dose (TD)= 51.8 Gy/28 fr, and PET-guided SIB on PET+ LNM to a median TD= 65.5 Gy. For 190 patients the primary treatment was surgery, and 108 of them had already been treated with ART/SRT, before the salvage treatment for nodal relapse. Median age at relapse was 71.3 (50.7-83.9) years. Median PSA was 1.97 (0.18-187.0) ng/ml. Median number of PET+ LNM was 2 (1-20). Androgen Deprivation Therapy was prescribed for 143 patients, for a median of 25.8 months, and 46 were CRPC Results With a median follow up of 60.9 (4.1-171.2) months, actuarial median biochemical relapse-free survival (bRFS) for HSPC patients was 47.3 months vs 13.6 months for CRPC. Median disease-free survival (DFS) was 136.3 vs 65.3 months, and median overall survival (OS) 137.6 vs 60.1 months. Two-, three- and five-year Kaplan Meyer estimates of biochemical relapse-free (bRFS), disease-free (DFS) and overall survival (OS) in HSPC vs CRPC are presented in Table 1. In patients without previous RT(at first LNM relapse) vs patients with previous ART/SRT (second relapse) actuarial median bRFS was 70.2 vs 20.3 months, median DFS was not reached for patients at first relapse vs 91.7 months for second relapse, and for OS, again, median OS was not reached for patients at first relapse vs 91.7 months for second relapse. Two-, three- and five-year Kaplan Meyer estimates of biochemical relapse-free (bRFS), disease-free (DFS) and overall survival (OS) for patients at first relapse vs second relapse are presented in Table 2. PO-1490 Prostate cancer nodal relapse: impact of CRPC and previous RT on salvage ENRT+PET guided SIB outcome