The correlation of Ga-68 PSMA, Tc-99m MDP whole body bone scintigraphy, F-18 FDG PET and post-therapy Lu-177 PSMA whole body imaging in metastatic castration resistant prostate cancer and their impact on prognostic prediction

In this study, we aimed to determine the correlation and prognostic impact of Gallium-68 prostate-specific membrane antigen positron emission tomography (Ga-68 PSMA PET/CT), Lutetium-177 prostate-specific membrane antigen radioligand therapy (Lu-177 RLT) whole-body scan scintigraphy (WBS), Technetium-99m methylene diphosphonate whole-body scintigraphy (Tc-99m MDP WBS), and Fluoro-18 deoxy glucose (F-18 FDG) PET/CT images in patients diagnosed with metastatic castration-resistant prostate cancer (mCRPC) who received Lu-177 RLT in our clinic. This might be provide contributions in patient management and clinical planning. Total 70 patients who diagnosed mCRPC which were followed and treated between July 2018 and June 2024 evaluated retrospectively and 49 of them met the inclusion criteria. Patients' age, gleason score, metastatic sites, prostate specific antigen (PSA) levels at different times, treatments received before first Lu-177 RLT, dates of progression and death, parameters obtained from different imaging techniques were recorded and analyzed statistically. We found a significant correlation between overall survival (OS) and age from the time of diagnosis, the presence of visceral metastases, PSA values before and after the first Lu-177 RLT, and the ratio of target lesion 1 and 2 mean pixel value (MPV)/parotid MPV after the Lu-177 TVT imaging. Secondly, xvi found a significant relationship between median OS after Lu-177 RLT and the presence of visceral metastases, the PSA value before and after first Lu-177 RLT. Thidly, found a significant correlation between median PFS after the first Lu-177 RLT and the presence of visceral metastases and PSA value of after the treatment of first Lu-177 PSMA. The cut-off values of PSA before and after the first Lu-177 RLT was found as ≥38.93 ng/mL, and ≥32.85 ng/mL respectively. In addition, we found a significant correlation between Ga 68 PSMA and Lu-177 TVT. We found that PSA levels of before and after Lu-177 RLT and different imaging parameters may be useful in predicting prognosis in mCRPC patients receiving Lu-177 RLT. We think that, this may have a potential to contribute to more effective patient management.