S1207
Clinical - Urology
ESTRO 2026
treated with definitive radiotherapy (RT). Material/Methods: A total of 87 patients who underwent RT for
intermediate- to high-risk PCa between 2016 and 2025 and were staged by pre-treatment 68Ga-PSMA PET-CT, were retrospectively analyzed. Patients received either conventional or moderately hypofractionated RT. The primary analysis evaluated the relationship between SUVmax, SUVmean, MV, and TL-PSMA values and the time to PSA nadir. Additional analyses explored associations between these parameters and clinicopathological factors using the Mann–Whitney U test and correlation analysis. Predictive values were examined through ROC analysis, and logistic regression analysis. All analyses were performed using SPSS v23, with p<0.05 considered statistically significant. Results: The median follow-up was 24 months (range: 6–64), and the median age at diagnosis was 74 years (range: 55–85). Median PSMA parameters were as follows: SUVmax 10.6 (range: 1–95), SUVmean 7.6 (range:2.5– 25), MV 5.6 (range:1.2–27), and TL-PSMA 35 (range:8– 288). Patient characteristics and PSMA parameter relationships are summarized in Table 1. SUVmax showed significant associations with baseline PSA, Gleason group, extraprostatic extension, seminal vesicle invasion, T stage, and nodal stage (all p<0.05). Among the other parameters, only TL-PSMA was associated with nodal stage (p=0.009). The median time to PSA nadir after RT was 6 months (range: 1–55). There was no significant correlation between SUVmax and time to PSA nadir (p>0.2). However, patients who reached PSA nadir after >6 months had significantly higher SUVmean and TL-PSMA values (p=0.007 and 0.004, respectively)(Fig.1). No significant relationship was found between MV and time to PSA nadir (p>0.3). In multivariate logistic regression, SUVmean, MV, and TL-PSMA were not independent predictors (p>0.05). ROC analysis demonstrated acceptable discriminatory ability for SUVmean (AUC=0.719, p=0.007) and TL- PSMA (AUC=0.735, p=0.004) in identifying patients with PSA nadir >6 months, while MV showed poor performance (AUC=0.592, p=0.2).
Conclusion: Although SUVmax measured by 68Ga-PSMA PET-CT correlates significantly with clinicopathological features, its predictive power for PSA kinetic after RT is limited. Conversely, SUVmean and TL-PSMA demonstrated higher prognostic potential in reflecting biochemical response kinetics. These findings highlight the importance of multidimensional evaluation of PSMA PET-CT parameters in prostate cancer. Keywords: Prostate cancer, PSMA, Suvmean, TL- PSMA, MV
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