Evaluation of Treatment Response in Prostate Cancer Patients: Analysis of Ga-68 PSMA PET/CT Parameters According to PROMISE Criteria

Evaluation of Treatment Response in Prostate Cancer Patients: Analysis of Ga-68 PSMA PET/CT Parameters According to PROMISE CriteriaAim: Gallium-68 (Ga-68) prostate-specific membrane antigen (PSMA) positron emission tomography/computed tomography (PET/CT) is superior to conventional methods for detecting prostate cancer lesions.However, there is still no standardized tool to quantify treatment response.Using the PROMISE criteria, which standardize lesion selection and disease staging, we evaluated the prognostic significance of Ga-68 PSMA PET/CT imaging parameters.Methods: Sixty-four patients who were referred for initial staging and for assessment of response using Ga-68 PSMA PET/CT were retrospectively included.For each primary tumor, lymph node metastasis, bone metastasis, and visceral metastasis, the highest PSMA expression was selected according to the PROMISE criteria.The quantitative PET/CT parameters (SUVmax, SUVmean, SUVpeak, TL-PSMA, and PSMA-TV) were calculated.Treatment response was then evaluated using PSMA PET progression criteria, which classify patients as progressors (exhibiting PSMA PET progression) or non-progressors.Receiver operating characteristic analysis was used to assess the predictive value of PET/CT parameters against biochemical response standards.Results: A significant difference was observed between progressors and non-progressors.In non-progressors, SUVmax, SUVmean, and SUVpeak decreased significantly in the prostate, lymph nodes, and visceral metastases.When miTNM was compared with PET/CT, significant differences were observed only for miT.SUVmax, SUVmean, and SUVpeak in the prostate showed strong correlations with response, highlighting the importance of assessing intensity-based changes in primary lesions.Conclusion: The PSMA PET progression criteria provide a robust framework for assessing response to therapy using Ga-68 PSMA PET/CT.miTNM staging is valuable for disease localization and extent, but our findings suggest it is less useful for monitoring response than for assessing changes in tumor intensity.We therefore recommend including PET parameters in routine response assessments.