ESTRO 2022 - Abstract Book

S532

Abstract book

ESTRO 2022

Purpose or Objective Patients with Gleason grade group(GG) 5 are known to have a significantly higher risk of biochemical failure(BF), distant metastases, and death compared to patients with lesser GGs. This study reports multi-institutional clinical outcomes of patients with non-metastatic GG5 treated with long-term ADT and high-dose external beam radiation image guided radiotherapy (RT). Materials and Methods 19 cancer centres were requested to report outcomes of non-metastatic GG5 prostate cancers treated with curative intent external beam radiation(EBRT), and with a minimum follow up of 18 months from the end of ADT. The key outcomes that were assessed were biochemical progression free survival(bPFS), metastases free survival(MFS) and overall survival(OS), acute and late gastrointestinal(GI) and genitourinary(GU) toxicities. The univariate(UVA) and multivariate analyses(MVA) to study the impact of prognostic factors were performed using log-rank and Cox proportional hazard model respectively. Results A total of 462 patients from 19 institutes were included in the study. 81% had T3/T4 disease, 31% had node-positive disease, 58% had Gleason 4+5, 30% had 5+4 and 12% had 5+5 disease. A third had PSMA PET-CT scan for staging and 77% had it for restaging at BF. The median duration of ADT was 24 months and 21% underwent surgical castration. The median EQD2 dose of RT was 75Gy, with 66% receiving either moderate or extreme hypofractionation and 71% receiving pelvic nodal RT. At a median follow-up of 4.6 years the 5 year bPFS, MFS and OS were 73.1%, 77.4% and 90.5% respectively. The 5-year prostate cancer-specific mortality was 6.7%. On UVA, primary Gleason 5 pattern, and pelvic node positivity were associated with worse bPFS and MFS; and medical castration with worse MFS. On MVA, only the primary Gleason 5 pattern was associated with worse outcomes with respect to all 3 endpoints (HR=0.49, 0.622, 0.469). Of the 115 patients who had a BF, the site of uptake on PSMA PET CT was prostate only, pelvis and distant in 19%, 23% and 84% respectively. Acute grade >2 GI and GU toxicities were noted in 21.9% and 31.9% respectively while late grade 2, 3 GI and GU toxicities were 12.1% and 3%; and 20.6% and 4.1% respectively. Conclusion Despite a high proportion of patients with advanced disease and GG5, high dose EBRT alone with long-term ADT leads to low rates of metastases and death from prostate cancer. The primary Gleason pattern 5 is associated with poor clinical outcomes compared to primary Gleason 4. The reported acute and late toxicities in a non-trial, community setting were comparable to the previously published prospective studies. N. Benziane 1 , P. Sargos 1 , T. Zilli 2 , A. Giraud 3 , G. Ingrosso 4 , M. Di Staso 5 , F. Trippa 6 , E. Meyer 7 , G. Francolini 8 , U. Schick 9 , J.M. Cosset 10 , E. Martin 11 , V. Ferrari 12 , V. Achard 13 , N. Giraud 1 , C. Pasquier 14 , N. Magné 15 , D. Pasquier 16 , S. Supiot 17 , I. Latorzeff 18 , K. Gnep 19 , P. Pommier 20 , T. Perennec 17 , H. Zaine 16 1 Institut Bergonié, Radiation Oncology, Bordeaux, France; 2 CHU Genève, Radiation Oncology, Geneve, Switzerland; 3 Institut Bergonié, Bio-statistique, Bordeaux, France; 4 University Of Perugia, Radiation Oncology, Perugia, Italy; 5 Nuovo San Salvatore, Radiation Oncology, l'Aquila, Italy; 6 Santa Maria Hospital, Radiation Oncology, Terni, Italy; 7 Centre Francois Beclesse, Radiation Oncology, Caen, France; 8 University of Florence, Radiation Oncology, Florence, Italy; 9 University Hospital Cavale Blanche, Radiation Oncology, Brest, France; 10 Groupe Amethyst, Radiation Oncology, Lagarenne Colombes, France; 11 Centre François Leclerc, Radiation Oncology, Dijon, France; 12 Centre Antoine Lacassagne, Medical Oncology, Nice, France; 13 CHU Genève, Radiation Oncology, Gevève, Switzerland; 14 Oncopole Toulouse, Radiation Oncology, Toulouse, France; 15 Institut de Cancérologie de la Loire, Radiation Oncology, Saint Etienne, France; 16 Centre Oscar Lambret, Radiation Oncology, Lille, France; 17 Centre de Cancérologie de l'Ouest, Radiation Oncology, Nantes, France; 18 Clinique Pasteur, Radiation Oncology, Toulouse, France; 19 Centre Eugène Marquis, Radiation oncology, Rennes, France; 20 Centre Léon Bérard, Radiation oncology, Lyon, France Purpose or Objective For prostate cancer (Pca), salvage radiotherapy (sRT) with or without androgen deprivation therapy (ADT) is currently the only curative treatment option in case of post-radical prostatectomy (RP) biochemical relapse (BR). Functional imaging techniques have shown that macroscopic recurrence (MR) in the prostate bed (PB) are frequent. In this study, we aimed to assess efficacy and safety of sRT in patients with MR inside the PB proven by functional imaging. Materials and Methods A multicenter retrospective study (SPIDER 01) was conducted in 16 European centers. Patients were included if they displayed BR after RP for Pca, with MR only in the PB proven by functional imaging. All patients had to be eligible for sRT. The overall population was divided along 4 groups according to the delivered treatment: dose escalation on MR (A), dose escalation on PB (B), double dose escalation MR+PB (C), no dose escalation (D). The primary endpoint was progression-free survival (PFS). Secondary outcomes included the metastasis-free survival (MFS), biochemical PFS (bPFS) and overall survival (OS). Grade ≥ 2 genito-urinary (GU) and gastro-intestinal (GI) acute and late toxicities were collected. Results Between January 2000 and December 2019, 363 patients with isolated MR after RP for Pca were treated by sRT. The median pre-sRT PSA level was 0.63ng/mL (range, 0.2-23.6). At the time of BR, 266 (73%) patients presented MR in the PB proven by magnetic resonance imaging, and 110 (30%) by positron emission tomography. The median follow-up was 53.6 months (range, 47.52; 58.32). The 5-year PFS and MFS were 70% (95%CI [63.8-75.4]) and 83.7% (95%CI [78.4-87.8]), respectively. Proffered Papers: Urology OC-0607 Radiotherapy guided by functional imaging for macroscopic local recurrence following prostatectomy