Diagnostic performance of 68 Ga-PSMA PET/CT in the detection of prostate cancer prior to initial biopsy: comparison with cancer-predicting nomograms

Abstract

Purpose: To assess the diagnostic performance of 68 Ga-PSMA PET/CT for detecting suspected prostate cancer (PCa) and to compare it with that of two cancer-predicting nomograms. Methods: We performed a retrospective analysis of 146 consecutive patients with suspected PCa based on symptoms or elevated total prostate-specific antigen (tPSA) levels who underwent 68 Ga-PSMA PET/CT and histopathologic examinations from April 2017 to April 2018 in a large tertiary care hospital in China. The 68 Ga-PSMA PET/CT results (PCa or benignancy) were evaluated by two experienced nuclear medicine specialists. The risk of positive PCa was evaluated using ERSPC and PCPT nomograms. The diagnostic performances of 68 Ga-PSMA PET/CT and that of the two nomograms were compared via receiver operating characteristic (ROC) curve analysis, decision curve analysis, and logistic regression. Results: A total of 58 patients with tPSA of 0.4–50 ng/ml were included in the final analysis; PCa diagnosis was confirmed in 37 patients and excluded in 21 patients. ROC analysis showed that the sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of 68 Ga-PSMA PET/CT were 91.67, 81.82, 89.19, and 85.71%, respectively, in per-patient analyses. 68 Ga-PSMA PET/CT exhibited a higher AUC (0.867) than those of ERSPC-RC3 (0.855) and PCPT-RC (0.770). The net benefit of 68 Ga-PSMA PET/CT was greatest for patients within threshold probabilities of 15–90%. Among the 58 patients, 11 (19%) biopsies suggested by ERSPC-RC3 were unnecessary and could have been avoided if judged by the 68 Ga-PSMA PET/CT results. Multivariate analysis revealed that the maximum standardised uptake value (SUV max ) and prostate volume were significant predictive factors for positive PCa results. Conclusion: In suspected PCa patients with tPSA of 0.4–50 ng/ml, 68 Ga-PSMA PET/CT outperformed the nomograms in predicting cancer and reducing unnecessary biopsies. In addition, the risk of PCa was positively correlated with a higher SUV max and lower prostate volume, which could help clinicians in making preliminary estimates of individual cancer risk, monitoring 68 Ga-PSMA PET/CT false-positive results and making biopsy decisions in daily medical practice.