Abstract / Summary
Purpose Multiple prostate-specific membrane antigen (PSMA) PET tracers are used for patient selection in radioligand therapy (RLT). This study compared treatment response to RLT across different PSMA tracers. Methods We retrospectively analyzed patients who underwent Lu-177 PSMA-617 RLT with baseline imaging using either Ga-68 PSMA-11 or F-18 DCFPyL PET. PET parameters were measured, including SUV mean , SUV max , and total tumor volume (TTV). Univariable and multivariable logistic regression analyses were performed to evaluate factors associated with PSA50 response, and Cox proportional hazards regression analyses were performed to evaluate factors associated with overall survival. Results Of 140 patients analyzed (Ga-68 PSMA-11: n=51; F-18 DCFPyL: n=89), SUV max and SUV mean did not differ significantly between groups; however, TTV was significantly higher in the Ga-68 PSMA-11 group (p=0.038). In multivariable analysis adjusted for age, baseline PSA, PET tracer type, SUVmean, and log-transformed TTV, PET tracer type was not significantly associated with PSA50 response (OR, 1.318; 95% CI, 0.585–2.970; p=0.505), whereas higher SUVmean was associated with greater odds of PSA50 response (OR, 1.285; 95% CI, 1.126–1.466; p<0.001). Overall survival did not differ significantly between tracer groups (HR, 0.760; 95% CI, 0.507–1.138; p=0.183), with median overall survival of 8.4 and 12.6 months. In multivariable analysis, PET tracer type was not significantly associated with overall survival (HR, 0.736; 95% CI, 0.475–1.139; p=0.168), whereas higher SUVmean was associated with a lower risk of death (HR, 0.886; 95% CI, 0.825–0.950; p<0.001) and higher log-transformed TTV was associated with a higher risk of death (HR, 1.415; 95% CI, 1.194–1.678; p<0.001). Conclusion PET tracer type was not significantly associated with PSA50 response or overall survival following RLT. Higher SUV mean was associated with greater odds of PSA50 response and a lower risk of death, whereas higher TTV was associated with overall survival.