Efficacy of 68Ga-PSMA PET/CT-derived whole-body volumetric parameters in predicting response to second-generation androgen receptor axis-targeted therapy, and the prognosis in metastatic hormone-refractory prostate cancer patients.

INTRODUCTION

The present study investigates the role of 68Ga-PSMA PET/CT-derived whole-body metabolic and volumetric parameters in the prediction of treatment response and prognosis among metastatic hormone-refractory prostate cancer patients undergoing second-generation androgen receptor axis-targeted therapy (abiraterone or enzalutamide).

MATERIALS AND METHODS

This retrospective study included 44 metastatic hormone-refractory prostate cancer patients undergoing 68Ga-PSMA PET/CT, including 29 enzalutamide-treated and 15 abiraterone-treated patients.

RESULTS

Of the 44 patients included in the study, 29 received enzalutamide and 15 received abiraterone. During treatment, the changes in PET parameters were correlated with the PSA (biochemical) response. More specifically, a positive correlation was noted between PSA response and percent change in TLP (ΔTLP) response, and there was concordance between the results (r = 0.652, k = 0.42, P < 0.001). Baseline PSA (P =0.05), high MTVw (P = 0.005), the increase in ΔPSA (P = 0.036), ΔTLP (P = 0.039) and percent change in MTV (ΔMTV) (P = 0.049) values were identified as factors associated with mortality risk.Multivariate analysis showed that PSA1 [odds ratio (OR): 1.005, 95% confidence interval (CI) 1.002-1.008, P = 0.004], ΔPSA (OR: 14.7, 95% CI 1.50-143.7, P = 0.02) and MTVw1 (OR: 11.4, 95% CI 1.11-116, 6, P = 0.04) were independent prognostic factors associated with mortality risk.

CONCLUSION

A statistically significant concordance and correlation was noted between 68Ga-PSMA PET/CT-derived whole-body metabolic parameters (ΔTLP and ΔMTV) and ΔPSA. In addition, the baseline PSA, ΔPSA, ΔTLP, ΔMTV and TMTV were identified as predictive factors for mortality risk.