S1242
Clinical - Urology
ESTRO 2026
Proffered Paper 2857 Post-hoc analysis of metastasis-free survival (MFS) and Eugonadal MFS in the RADIOSA phase II randomized trial Giulia Marvaso 1,2 , Maria Giulia Vincini 1 , Chiara Lorubbio 1 , Cristiana Fodor 1 , Stefano Luzzago 3 , Alessandro Francesco Mistretta 3,2 , Giuseppe Petralia 4 , Nicola Fusco 5,2 , Gabriella Pravettoni 6,2 , Gennaro Musi 3,2 , Chad Tang 7 , Phuoc Tran 8 , Piet Ost 9 , Barbara Alicja Jereczek-Fossa 1,2 1 Division of Radiation Oncology, Istituto Europeo di Oncologia IRCCS, Milan, Italy. 2 Department of Oncology and Hemato-oncology, University of Milan, Milan, Italy. 3 Division of Urology, Istituto Europeo di Oncologia IRCCS, Milan, Italy. 4 Division of Radiology, Istituto Europeo di Oncologia IRCCS, Milan, Italy. 5 Division of Pathology, Istituto Europeo di Oncologia IRCCS, Milan, Italy. 6 Division of Applied Research for Cognitive and Psychological Sciences, Istituto Europeo di Oncologia IRCCS, Milan, Italy. 7 Department of Genitourinary Radiation Oncology, , MD Anderson Cancer Center,, Houston, TX,, USA. 8 Department of Genitourinary Radiation Oncology, MD Anderson Cancer Center,, Houston, TX,, USA. 9 Department of Radiation Oncology, , Iridium Network,, Wilrijk, Belgium Purpose/Objective: Metastasis-free survival (MFS) has been validated as a surrogate endpoint for overall survival in non- metastatic prostate cancer, and may represent an adaptable and clinically meaningful endpoint in oligorecurrent disease. The phase II RADIOSA trial (ref 1) compared stereotactic body radiotherapy (SBRT) alone (Arm A) versus SBRT plus 6-month androgen deprivation therapy (ADT, Arm B). This post-hoc analysis evaluated MFS and eugonadal MFS after testosterone recovery, with a visual mapping of disease trajectories through a Sankey diagram. Material/Methods:
A total of 102 patients were randomized 1:1 to Arm A (SBRT) or Arm B (SBRT + ADT). Median follow-up (Reverse KM) was 49.23 months (95% CI 42.47– 54.8). MFS was defined as the time between randomisation and the appearance of a metastatic recurrence (any M1) on imaging.Eugonadal MFS was calculated from testosterone recovery to new metastasis or last follow-up. Kaplan–Meier (KM) survival curves were compared with log-rank tests; hazard ratios were estimated using Cox models. Results:
Metastatic progression (Figure 1a) occurred in 32/51 (62.7%) patients in Arm A and 19/51 (37.3%) in Arm B. Median MFS was 16.6 months (95% CI 12.83–NA) in Arm A and not reached in Arm B, with a 61% risk reduction for metastatic progression (log-rank test, p = 0.00079; HR 0.3894, 95% CI 0.2201–0.6888, p = 0.00119). All patients enrolled in arm B, except two, reached testosterone recovery within the follow- up period. After testosterone recovery, eugonadal MFS remained significantly longer in Arm B (Figure 1b, p < 0.05), confirming that the advantage of the
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