ESTRO 2023 - Abstract Book

S1224

Digital Posters

ESTRO 2023

PO-1506 FIRST BRC AFTER RP: choline/PSMA-PET or mpMRI guided-SBRT on DETECTABLE PROSTATE BED RECURRENCE

R. Santamaria 1,2 , L. Colombi 1,3 , G. Corrao 1 , M. Zaffaroni 1 , M.G. Vincini 1 , D. Zerini 1 , L. Muraglia 4 , S. Alessi 5 , G. Marvaso 1,3 , F. Ceci 4,3 , G. Petralia 5,3 , G. Musi 6 , B.A. Jereczek-Fossa 1,3 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 University of Milan, Department of Oncology and Hemato-Oncology, Milan, Italy; 4 IEO, European Institute of Oncology IRCCS, Division of Nuclear Medicine, Milan, Italy; 5 IEO, European Institute of Oncology IRCCS, Division of Radiology, Milan, Italy; 6 IEO, European Institute of Oncology IRCCS, Division of Urology, Milan, Italy Purpose or Objective Local recurrence on prostate bed occurred in about 30% of PCa patients after surgery. Diagnostic imaging has made significant advances in recent years, expanding and refining the diagnostic potential and enabling precise detection of disease recurrence. However, the most appropriate diagnostic approach and salvage radiotherapy for this clinical setting remains a matter of debate. Stereotactic RT (SBRT) treatments made it possible to target only the tissue affected by the recurrence, achieving excellent local control with an optimal safety profile. The aim of the present study (Ethical Committee notification Nr 79) is to evaluate the efficacy and safety of our cohort of patients treated with SBRT on the detectable prostate bed recurrence. Materials and Methods Patients who underwent SBRT to macroscopic bed recurrence were retrospectively considered. All patinets were treated based on multiparametric (mp) MRI or choline/PSMA PET. Continuous variables were summarized as mean/median and interquartile range/range, while categorical variables were presented with absolute and relative frequencies. Toxicities were collected according RTOG scale. Results A total of consecutive 29 patients were included for the analysis. Among them 19 (65.5%) presented a T3 disease at surgery, 20 (69%). Nine (31%) and 20 (69%) had negative and positive surgical margins and the majority without perineural invasion (69%). Fourteen (48.3%) patients were diagnosed with a grade 3 ISUP. Median time to biochemical relapse was 47.9 months (3.4-157.2). Median PSA at restaging was 0.5 ng/ml (0.08-26.89). Thirteen patients (45%) were staged with both mpMRI and choline/PSMA PET, while 6 (20%) and 10 (35%) were treated based on PET or MRI only, respectively. All patients underwent SBRT on prostate in 5 fx every other day with a dose/fx within 6 or 7 Gy. Only 2 (7%) patients underwent concomitant hormonal therapy. After a median follow-up of 11.8 months (6.8-53.9), 10 (35%) patients experienced a biochemical relapse. Among them, 8 (27.5) developed a clincal recurrence (4 local recurrences and 4 oligorelapses). At last censored follow-up, 11 (38%) patients are alive with disease while 14 (48.3%) are alive with no evidence of disease. Five (17%) G1 gastrointestinal (GI) acute toxicity were observed and 8 (27.5%) G2 genitourinary (GU) toxicities were reported. No G ≥ 3 GU/GI acute toxicities were noted. One acute G2 toxicity occurred. All toxicities were solved at last follow up.