Baseline Ga-68 PSMA PET/CT-derived volumetric parameters as predictors of biochemical recurrence following radical...

This study aimed to investigate the prognostic value of volumetric parameters derived from staging Ga-68 PSMA PET/CT imaging in predicting biochemical recurrence (BCR) among prostate cancer patients treated with radical prostatectomy.

This retrospective study included 217 patients diagnosed with prostate cancer between March 2018 and October 2024 who underwent preoperative Ga-68 PSMA PET/CT, subsequent radical prostatectomy, and had regular follow-up data available. Semiquantitative (SUVmax, SUVmean) and volumetric (PSMA-TV, TL-PSMA, wbPSMA-TV, wbTL-PSMA) parameters for both the primary prostate lesion and the whole body were calculated from the images. The primary endpoint was defined as biochemical progression-free survival (bPFS). ROC curve, Kaplan-Meier, and Cox regression analyses were utilized to evaluate prognostic performance.

Ga-68 PSMA PET/CT volumetric parameters, particularly wbPSMA-TV and wbTL-PSMA, were found to be significantly higher in patients who developed BCR. Univariate Cox regression analysis revealed that both volumetric and semiquantitative parameters were significantly associated with biochemical progression. However, in the multivariate analysis, volumetric parameters did not emerge as independent predictors; instead, prostate SUVmean, ISUP grade group, and positive surgical margin status were identified as independent prognostic factors. Addition of prostate SUVmean to a clinical model modestly improved discrimination (C-index: 0.587 vs. 0.608) and significantly improved model fit (p = 0.004). Furthermore, prostate SUVmax and SUVmean values demonstrated significant performance in predicting early biochemical progression occurring within the first year post-surgery.

Although Ga-68 PSMA PET/CT-derived volumetric parameters were associated with biochemical progression, they were not validated as independent prognostic factors. Conversely, semiquantitative parameters-most notably prostate SUVmean-demonstrated independent prognostic value and may be significant indicators for predicting early biochemical progression. These findings suggest that prostate SUVmean and SUVmax could serve as complementary, preoperatively available indicators of early BCR risk when integrated with established clinicopathological factors, although their modest discriminative performance warrants external validation before clinical application.