Clinical decision impact of 18F-PSMA-1007 PET/CT for prostate cancer staging: Avoiding over- and under-treatment versus bone scintigraphy.

Abstract

e15088 Background: For medical oncologists and multidisciplinary teams, staging is not descriptive - it determines treatment intent, intensity, and eligibility for metastasis-directed strategies. Bone scintigraphy can misclassify metastatic status, driving both unnecessary systemic therapy and delayed intensification when occult disease is missed. We assessed whether 18F-PSMA-1007 PET/CT meaningfully changes staging and, consequently, oncology management compared with bone scintigraphy in real-world practice. Methods: We conducted a single-center observational study at European Medical Center (Moscow) from 2018 to 2025 to assess the clinical impact of adding 18F-PSMA-1007 PET/CT to conventional staging in prostate cancer. Bone scintigraphy was performed according to the institutional staging/follow-up pathway, and 18F-PSMA-1007 PET/CT was additionally performed under a predefined research protocol to enable within-patient comparison. Overall, 604 patients underwent PSMA PET/CT during the study period (a total of 976 scans); the comparative cohort comprised 107 patients who underwent both bone scintigraphy and 18F-PSMA-1007 PET/CT. The primary endpoint was metastatic stage reclassification after PSMA PET/CT versus bone scintigraphy (M0→M1 or M1→M0). A prespecified analysis was performed in the high-risk subgroup. Proportions are reported with 95% confidence intervals. Results: PSMA PET/CT altered staging in 44/107 patients (41.1%; 95% CI 32.3-50.6). Upstaging occurred in 34/107 (31.8%) due to previously unrecognized metastatic lesions, while downstaging occurred in 10/107 (9.3%) by excluding false-positive findings on bone scintigraphy. The effect was most pronounced in high-risk patients (n = 51) where restaging was observed in 32/51 (62.7%; 95% CI 49.0-74.7). Among patients with suspected metastatic bone disease on bone scintigraphy (n = 30), PSMA PET/CT excluded systemic involvement in 10/30 (33.3%), supporting avoidance of unnecessary systemic therapy and preserving curative-intent local treatment options. Conclusions: 18F-PSMA-1007 PET/CT produced clinically meaningful stage migration versus bone scintigraphy in routine prostate cancer care, with the largest impact in high-risk disease. By both revealing previously unrecognized metastases and excluding false-positive bone scan findings, PSMA PET/CT can reduce over- and under-treatment and improve selection for curative-intent local therapy versus systemic/combined strategies. Given cost and resource implications, PSMA PET/CT should be applied in a risk-adapted manner, with prioritization of high-risk patients where the decision impact appears greatest. Larger prospective studies are needed to define optimal selection criteria and to validate clinical and outcomes benefits of this approach.