miPSMA Score in 68Ga-PSMA PET-CT: An Institutional Review from Pakistan

Abstract Prostate cancer is the second most common cancer in men and a leading cause of cancer-related death worldwide. Accurate staging is essential for effective treatment. The use of gallium-68 (68Ga)-prostate-specific membrane antigen (PSMA) positron emission tomography-computed tomography (PET-CT), a highly sensitive and specific imaging technique, has increased for staging and detecting biochemical recurrence in prostate cancer patients. This retrospective study evaluated 68Ga-PSMA PET-CT scans of 78 patients with histologically confirmed prostate adenocarcinoma acquired between December 2019 and April 2021. Gleason grade group, prostate-specific antigen level, National Comprehensive Cancer Network (NCCN) risk, American Joint Committee on Caner (AJCC) stage, and treatment history were reviewed, with follow-up until December 2024. The lesions were scored visually using the molecular imaging PSMA (miPSMA) score and maximum standardized uptake value (SUVmax) was measured. Data were analyzed in SPSS 27.0 using chi-square, Kruskal–Wallis, and Kaplan–Meier tests, with a p-value of ≤ 0.05 considered significant. The mean age of the patients was 66.5 ± 8.9. 68Ga-PSMA PET-CT altered the management of 48% of patients, upstaging the disease in 79% of these cases by identifying additional metastatic sites. SUVmax had a positive association with miPSMA score (p < 0.05), but not with Gleason grade group, AJCC stage, NCCN risk, or age. At 37-month follow-up, 54% were alive and 13% had died. Exploratory analysis showed that higher miPSMA score was associated with overall poor survival rates. We also detected incidental lesions later diagnosed as second primary cancers in two patients, including renal cell carcinoma and hepatocellular carcinoma. Our institutional experience with 68Ga-PSMA PET-CT showed a major impact on management, altering treatment in nearly half of patients through disease upstaging or downstaging. miPSMA score showed association with SUVmax but not with Gleason grade group, AJCC stage, NCCN risk, or age. Exploratory findings suggest a possible association between higher primary tumor miPSMA scores and poorer survival outcomes.