Search

Objective: We evaluated the impact of 68Ga-PSMA PET/CT (PSMA PET) on therapy management of newly diagnosed highrisk prostate cancer (PCa). Material and Method: Patients who underwent a PSMA PET for primary staging of high-risk PCa were evaluated retrospectively. Patients had abdominopelvic CT (n=126), pelvic MRI (n=42) and bone scintigraphy (BS) (n=40) prior to PSMA PET. All clinical, biochemical, and imaging data were documented. Increased PSMA uptakes related to PCa were documented according to previously described PSMA-RADS version 1.0 based on a fivepoint scale. The impact of PSMA PET on patient management was evaluated through pre and post PET/CT questionnaires, retrospectively. Management changes were categorized as inter or intramodality change, based on PSMA PET results. Paired samples t-test was used to compare subgroups in SPSS version 24.0 software. A p-value <0.05 was considered significant. Results: A total of 126 patients were included in the study. The median PSA level was 30.8 ng/ml (95%CI: 2.1-268.6 ng/ml) and median GS was 8 (range: 6-10). Based on the PSMA PET findings, 41 patients (32.5%) had more extensive disease and 2 patients (1.6%) had less extensive disease. Overall, therapy management was changed in 38 patients (30.1%). Intermodality changes occurred in 29 patients (23%), and intramodality changes occurred in 9 patients (7.1%). The change in management was similar in patients with BS and without BS, 30% vs. 30.2%. Conclusion: PSMA PET impacted the therapy management in almost one-third of patients in high-risk PCa even though they had already been staged with standard imaging modalities. [ABSTRACT FROM AUTHOR]

Background: The aim of this study is to clarify the critical organs that limit treatment scheme and also evaluate the validity of currently used critical organ threshold values in neuroendocrine tumor (NET) patients, receiving peptide receptor radionuclide therapy (PRRT) with Lutetium 177 ( 177 Lu)-DOTATATE. Materials and Methods: Thirty-six NET patients (ages 16-73 years) who received 177 Lu-DOTATATE treatment were evaluated retrospectively in this study. Dosimetric calculations were made using medical internal radionuclide dose method. For calculation of organ doses, Internal Dose Assessment at Organ Level/Exponential Modelling 1.1 software program was used. Follow-up data were used to determine the organ failure. Results: A total of 141 cycles and mean of 3.91 (±1.33) cycles were applied to the patients. A mean of 691 mCi (±257 mCi) 177 Lu-DOTATATE infusion in total and a dose between 70 and 200 mCi per treatment was applied to patients. Seven of 36 patients reached 23 Gy renal dose limit. In these patients, although kidney doses were between 23 and 29 Gy, there was no diminution in renal functions during follow-up. Two of 36 patients reached total bone marrow dose of 2 Gy limit. Bone marrow suppression did not develop in these patients. Conclusion: The critical organs that seem to affect the treatment scheme in PRRT with 177 Lu-DOTATATE are kidney and bone marrow. Although there are established threshold levels, derived from radiotherapy experience, more studies are needed to clarify these dose limits in systemic radionuclide therapies such as PRRT.