18F-PSMA-1007 PET/CT tumor volume quantification: a game-changing prognostic biomarker for first-line ARPI therapy in metastatic castration-resistant prostate cancer.

PURPOSE: This study evaluates the prognostic value of baseline 18F-PSMA-1007 PET/CT-derived volumetric metabolic parameters in metastatic castration-resistant prostate cancer (mCRPC) patients initiating first-line androgen receptor pathway inhibitor (ARPI) therapy, while exploring their relationship with serum PSA and developing a risk stratification model.

RESULTS

Both wbPSMA-TV (r = 0.70) and wbTL-PSMA (r = 0.67) correlated with baseline PSA. Multivariable analysis identified bone metastasis count (adjusted OR [aOR] 0.19, 95% CI 0.11-0.35; P < 0.001) and wbPSMA-TV (aOR = 0.77, 95% CI 0.65-0.91; P < 0.001) as independent predictors of early PSA response. Baseline wbTL-PSMA ≥ 231.4 SUV cm3 independently predicted shorter OS (10.3 vs. 22.2 months, P < 0.001). Multivariable Cox regression confirmed wbTL-PSMA (adjusted hazard ratio [aHR] 3.160, 95% CI 2.490-4.016; P < 0.001), wbPSMA-TV (aHR 3.010, 95% CI 2.467-3.683; P < 0.001), number of bone metastases (aHR 2.510, 95% CI 1.893-3.148; P < 0.001), and PSA level (aHR 2.995, 95% CI 2.810-3.190; P < 0.001) as OS determinants. The RF model stratified patients into low- (median OS not reached), intermediate-(11.8 months), and high-risk (9.55 months) groups (P < 0.001).

CONCLUSION

Baseline 18F-PSMA-1007 PET/CT-derived volumetric parameters (wbPSMA-TV and wbTL-PSMA) serve as independent prognostic biomarkers for survival in mCRPC patients receiving ARPI therapy. Integration of these metrics with clinical variables enhances risk stratification, potentially guiding personalized therapeutic strategies. Prospective validation is warranted to confirm clinical utility.