Diagnostic Performance of 99mTc Bone Scintigraphy in the Staging of Prostate Cancer

justin.pieterse@uct.ac.za Introduction: 99m Tc MDP bone scintigraphy has utility in staging prostate cancer where access to more accurate modalities, such as PSMA ligand imaging, is limited by cost or lacking infrastructure. The aim of the study was to establish what proportion of patients under evaluation for possible radical therapy demonstrated skeletal metastases on staging bone scan and to establish whether further motivation might exist for more appropriate utility of bone scan in particular patient cohorts as per risk stratification parameters, and age. Methods: Patients with high-intermediate to high-risk prostate cancer patients under evaluation for possible radical therapy were referred to our unit for staging bone scan. Studies were done between September 1, 2019, and February 29, 2020. Image findings were categorized as positive, or negative, for evidence conclusive of metastases. Standard prostate cancer risk stratification parameters together with patient age were also collected. Data were analyzed for statistically significant relationships between diagnostic performance and the aforementioned parameters. The associations between image findings and clinical stage, histology grade, PSA level, and age were assessed. Results: Eighty-seven patients were included, of which 38% ( n = 33) had bone scintigraphy positive for skeletal metastases. Clinical stage was significantly associated with image findings ( p = 0.018). Patients with a positive bone scan were significantly more likely to have clinical stage cT3/4 cancer compared with patients with a negative scan (54.5% vs. 18.5%). Patients who tested positive were significantly more likely to have a histology grade ISUP 5 and less likely to be ISUP 3 ( p = 0.005). Patients who tested positive had a significantly higher mean PSA levels (275.2 vs. 45.5 µg/L; p < 0.001) and mean age (68.2 vs. 63.2 years; p = 0.001) compared with those who tested negative. Conclusion: Bone scan is more appropriately utilized in patients with stage cT3/4 disease, ISUP grade 5 histology, older age (> 68 years), and higher spectrum PSA levels. Publication History Article published online: 25 May 2023 © 2023. The Author(s). This is an open access article published by Thieme under the terms of the Creative Commons Attribution License, permitting unrestricted use, distribution, and reproduction so long as the original work is properly cited. (https://creativecommons.org/licenses/by/4.0/) Thieme Medical and Scientific Publishers Pvt. Ltd. A-12, 2nd Floor, Sector 2, Noida-201301 UP, India