ESTRO 2023 - Abstract Book

S1228

Digital Posters

ESTRO 2023

Conclusion The current model may help clinicians to identify those pts whose social activity could be more severely affected by treatment 2 years after RT with PNI. Results suggest that the risk of late relevant decline of SOCIAL Domain may be expected in pts with higher baseline SOCIAL score, more severe acute worsening of bowel symptoms and submitted to adjuvant RT.

PO-1510 PSMA-PET and PCa: an exploratory analysis beyond the numerical definition of oligometastatic state

M.G. Vincini 1 , G. Corrao 2 , M. Zaffaroni 2 , C. Lorubbio 2,3 , F. Mastroleo 2,4 , L. Muraglia 5 , C. Fodor 2 , F.A. Mistretta 6 , S. Luzzago 6 , G. Musi 6,3 , G. Marvaso 2,3 , B.A. Jereczek-Fossa 2,3 1 IEO, European Institute of Oncology, IRCSS, Division of Radiation Oncology , Milan, Italy; 2 IEO, European Institute of Oncology, IRCSS, Division of radiation oncology , Milan, Italy; 3 University of Milan, Department of Oncology and Hematoncology, Milan, Italy; 4 University Hospital Maggiore della Carità, Division of Radiation Oncology, Novara, Italy; 5 IEO, European Institute of Oncology, IRCSS, Division of nuclear medicine, Milan, Italy; 6 IEO, European Institute of Oncology, IRCSS, Division of Urology, Milan, Italy Purpose or Objective Oligometastatic characterization usually relies only on the number of radiologically detectable localizations. A deeper understanding of the burden of disease is needed to offer the best tailored treatment. The aim of this study is to evaluate the predictive value of volumetric parameters derived from prostate-specific membrane antigen/PET (PSMA-PET) in oligorecurrent PCa patients. The study is a spin-off analysis of the ongoing phase II randomized trial RADIOSA (NCT03940235). Materials and Methods Patients enrolled within the RADIOSA trial who underwent PET-PSMA at first biochemical recurrence were included. Two experienced nuclear medicine physicians retrospectively reviewed PSMA-PET images blinded to all histopathological and clinical data. PSMA-PET quantitative parameters PSMA tumor volume (PSMA-TV) and Maximum standardized uptake values (SUVmax) were collected. Patients were stratified according to these two parameters using the 3rd quartile of collected values as cut-off, and PSA at the first diagnosis, PSA at the first recurrence, and time between the first diagnosis and the first recurrence were compared. The site of oligometastases (bone or lymph nodal) was evaluated to assess any relation with the considered PSMA-PET quantitative parameters. Results Among the 89 enrolled patients, a total of 29 met the inclusion criteria. Mean PSA at the first diagnosis and at the first recurrence were 10.2 ng/mL and 2.8 ng/mL, respectively. Median time between first diagnosis and first recurrence was 51.43 months. A total of 16 patients had lymph nodal metastases only in PSMA-PET, while 13 had at least one bone metastases. Considered variables across the different groups are shown in Table 1 and Figure 1.