Risk of bone metastases on [18F]NaF PET/CT in 734 patients with newly diagnosed prostate cancer

Abstract Purpose International guidelines recommend assessment for bone metastases in patients with high-risk prostate cancer (PC) and those with unfavourable intermediate-risk disease. These recommendations are largely based on studies using planar bone scintigraphy. We aimed to assess the diagnostic accuracy of [ 18 F]sodium fluoride ([ 18 F]NaF) PET/CT in newly diagnosed PC. We also evaluated the clinical utility of routine bone imaging in patients with unfavourable intermediate-risk disease and International Society of Urological Pathology grade group (ISUP GG) 3. Methods This retrospective single-center study included 734 consecutive patients with newly diagnosed PC who underwent [ 18 F]NaF PET/CT for primary staging. Patients were classified according to the current European Association of Urology risk classification, with the intermediate-risk subgroup restricted to patients with ISUP GG 3. All scan reports were retrospectively reviewed, and patient-level findings regarding bone metastases were validated against a reference standard based on follow-up imaging and clinical data. Sensitivity, specificity, and predictive values were calculated. Results Of the 734 patients, 607 (83%) had high-risk disease and 127 (17%) had intermediate-risk disease with ISUP GG 3. Overall, bone metastases were detected in 225 patients (31%). Among high-risk patients, 224 (37%) had bone metastases, whereas only 1 of 127 intermediate-risk patients (0.8%) had bone metastases on [ 18 F]NaF PET/CT. Follow-up identified one additional potential false-negative case in the intermediate-risk group. Among patients with a conclusive reference standard ( n = 689), sensitivity and specificity were 0.90 and 0.99, respectively. Conclusion [ 18 F]NaF PET/CT demonstrates high diagnostic accuracy for the detection of bone metastases in newly diagnosed PC. However, given the very low prevalence of bone metastases, its clinical utility in patients with unfavourable intermediate-risk disease and ISUP GG 3 appears limited.