S1247
Clinical - Urology
ESTRO 2026
5 Radiotherapy Department, Institut de Cancérologie de l'Ouest, Nantes, France. 6 Radiation Oncology Department, Centre Georges-François Leclerc, Dijon, France. 7 Radiation Oncology Department, Centre Leon Berard, Lyon, France Purpose/Objective: Salvage local therapy, particularly in its focal form, is increasingly offered to patients presenting with intraprostatic recurrence after radiotherapy. However, data remain limited on the relative contribution of multiparametric (mp) MRI and biopsy to target delineation (1,2). To compare mpMRI, systematic and MRI-targeted biopsies for detecting intraprostatic cancer. Material/Methods: Seventy patients screened or enrolled in the GETUG- 31 trial of focal SBRT reirradiation were included in this ancillary study. Patients presented with intraprostatic recurrence after external beam radiotherapy for low- or intermediate-risk prostate cancer. The baseline assessment consisted of an mpMRI, choline PET/CT, and combined targeted and systematic biopsies of both prostatic lobes (minimum of 12 cores). The estimated CTV was required to be less than half of the prostate volume. The location of positive biopsies and mpMRI-suspected lesions was recorded according to the 27-sector ISUP prostate map. Sensitivity of mpMRI was calculated considering biopsy as gold standard. Results: Median PSA at screening was 4.0 ng/mL (range: 2-13) and median PSA doubling time was 25.5 months. Median number of biopsies was 14 (12-44) and median number of positive biopsies was 3 (1-8). The ISUP grade group (n=68) was 1, 2, 3, 4, and 5 in 12 (18%), 25 (37%), 19 (28%), 7 (10%), and 5 (7%) of patients, respectively. Histologic analysis showed positive cores in 16 (23%), 20 (29%), 11 (16%), 15 (21%), and 8 (11%) patients involving 1, 2, 3, 4, and ≥ 5 prostate sectors, respectively. Positive sites were located in the base in 33 (47%) of patients, mid-gland in 53 (76%), and apex in 39 (56%). mpMRI identified suspicious lesions in 22 (31%), 26 (37%), 5 (7%), 7 (10%), and 10 (14%) patients involving 1, 2, 3, 4, and ≥ 5 prostate sectors, respectively. Suspicious MRI lesions were located in the base in 26 (37%) patients, mid- gland in 47 (67%), and apex in 34 (49%). mpMRI failed to identify at least one biopsy-positive sector in 33/70 (47%) patients; 17 (24%) had one missed sector, and 16 (23%) had two or more. Overall, 14 (20%) patients had at least one missed sector non-adjacent to the detected invaded sector(s). Figure 1 shows a sector- based overview of biopsy and mpMRI findings for each patient. A limitation of our study is the absence of PSMA PET imaging, which was not available in France during the enrollment period.
Results: Up to date, 84 patients have been enrolled, with a median follow-up of 24 months (95% CI, 21–26).CBR and BR at 3 months after treatment were achieved in 46 (54.8%) and 71 (84.5%) patients.Biochemical progression after treatment was reported in 21 patients, while metastases occurrence and ADT start were reported in 13 patients each. Median bPFS, rPFS and aPFS was not reached for these endpoints. Acute grade 2 gastrointestinal (GI) and genitourinary (GU) adverse events occurred in 2 patients each, late adverse events included 2 cases of grade 2 GU and 1 case of grade 2 GI . No grade ≥ 3 were reported.CBR was not associated with a statistically significant improvement in BR (HR 1.36; 95% CI, 0.57– 3.22), rPFS (HR 1.51; 95% CI, 0.50–4.50), or aPFS (HR 2.20; 95% CI, 0.73–6.60), with median survival not reached across all subgroups. Conclusion: Findings indicate encouraging outcomes following SSRT in patients with macroscopic prostate bed recurrence, supporting the feasibility and effectiveness of this approach . Rate of biochemical responses were promising, particularly given the omission of concomitant ADT within the study protocol. Reported adverse events were mild, underscoring the favourable safety profile of SSRT. Longer follow up is needed to confirm the results after this approach. References: 1)Schröder, C.; Tang, H.; Windisch, P.; Zwahlen, D.R.; Buchali,A.; Vu, E.; Bostel, T.; Sprave, T.; Zilli,T.; Murthy, V.; et al.Stereotactic Radiotherapy after Radical Prostatectomy in Patients with Prostate Cancer in the Adjuvant or Salvage Setting: A Systematic Review. Cancers 2022, 14, 696.2)Francolini, G.; Jereczek-Fossa, B.A.; Di Cataldo, V.;Simontacchi, G.; Marvaso, G.; Gandini, S.; Corso, F.; Ciccone,L.P.; Zerella, M.A.; Gentile, P.; et al. Stereotactic or conventional radiotherapy for macroscopic prostate bed recurrence: A propensity score analysis. La Radiol. Medica 2022, 127, 449–457. Keywords: prostate cancer,SBRT,cyberknife Poster Discussion 3082 Comparison of mpMRI and Biopsies for Identifying Radiorecurrent Prostate Cancer: GETUG-31 Ancillary Study David Pasquier 1,2 , Emmanuelle Tresch 3 , Meryem Brihoum 4 , Marie Cécile Le Deley 3 , Stephane Supiot 5 , Magali Quivrin 6 , Cecile Laude 7 , Eric Lartigau 1,2 1 Academic Department of Radiation Oncology, Centre O. Lambret, Lille, France. 2 Lille University, CRIStAL UMR 9189, Lille, France. 3 Methodology and Biostatistics Unit, Centre O. Lambret, Lille, France. 4 Urogenital Tumor Study Group (GETUG), Unicancer, Paris, France.
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