Role of volumetric parameters obtained from 68 Ga-PSMA PET/CT and 18 F-FDG PET/CT in predicting overall survival in patients with mCRPC receiving taxane therapy

Objective The aim of this study was to determine the prognostic role of volumetric parameters and Pro-PET scores obtained from 68 Ga-prostate-specific membrane antigen (PSMA) PET/CT and 18 F-FDG PET/CT in patients with metastatic castration-resistant prostate cancer (mCRPC) receiving taxane therapy. Materials and methods The study included 71 patients who underwent simultaneous PSMA and 18 F-FDG PET/CT imaging between January 2019 and January 2022, had a Pro-PET score of 3–5 and had received taxane therapy after imaging. 18 F-FDG tumor volume (TV-F) and PSMA tumor volume (TV-P) values of the lesions and total lesion glycolysis (TL-G) and total lesion PSMA (TL-P) values of the lesions were calculated on both imaging studies and the effects of these parameters on overall survival (OS) were investigated. Results The median age of the patients included herein was 71 years (56–89) and the median prostate-specific antigen (PSA) level was 16.4 (0.01–1852 ng/dL). According to the Kaplan–Meier survival analysis, TTV-P ≥ 78.5, TTL-P ≥ 278.8, TTV-F ≥ 94.98, TTL-G ≥ 458.3, TTV-P + F ≥ 195.45, TTL-G + P ≥ 855.78, lymph node (L)TV-FDG ≥ 3.4, LFDG-SUVmax ≥ 3.2, LFDG-SUVmean ≥ 2.25, LFDG-SUVpeak ≥ 2.55, and bone (B)TV-F ≥ 51.15 values were found to be prognostic factors in predicting short OS. Multivariate Cox regression analysis showed that a Vscore ≥ 3 (95% confidence interval [CI]: 7.069–98.251, p < 0.001) and TTL-G + P ≥ 855.78 (95% CI: 4.878–1037.860, p = 0.006) were found to be independent prognostic factors in predicting short OS. Conclusion Volumetric parameters and Pro-PET scores obtained from 68 Ga-PSMA PET/CT and 18 F-FDG PET/CT imaging have been shown to have an impact on OS in patients with mCRPC receiving taxane therapy.