| Background:Prostate cancer(PCa)is the most common type of malignant tumor and the second leading cause of cancer-associated mortality among men worldwide.Currently,PCa has been the cancer with fastest grow rate among male-malignant tumors in china,which requiring professional and effective measures.The total prostate-specific antigen(tPSA)is the most widely used biomarker for screening and early detection of PCa.However,the benefit of tPSA remains debatable owing to its organ specificity rather than tumor specificity and its low specificity in the detection of PCa patients with low level of tPSA.This issue has led to overdiagnosis and unnecessary prostate biopsies,which are invasive examinations associated with higher costs and adverse effects.Effective measures should be taken to reduce the such complications and economic burden.Currently,multiple Nomograms incorporating tPSA and other clinical predictors have been developed to predict the likelihood of a positive biopsy result.Among established Nomograms,the European Randomized Study of Screening for Prostate Cancer(ERSPC)risk calculator(RC)and the American Prostate Cancer Prevention Trial(PCPT)RC are currently the most used and can help to reduce the complications and costs incurred by unnecessary biopsy.In recent years,in addition to cancer Nomograms,68Ga prostate-specific membrane antigen positron emission tomography/computerized tomography(68Ga-PSMA PET/CT)has earned widespread attention as a novel imaging modality based on molecular-level analysis,rather than morpho-logical or physiological analysis,to assist in PCa diagnosis and tumor burden evaluation.Recently,68GaPSMA PET/CT has been used to aid decision making by confirming or eliminating the need for biopsies.A previous study showed that 11C-choline PET/CT outperformed PCa Nomograms in diagnosing lymph node metastasis.However,to our knowledge,no previous studies have compared 68Ga-PSMA PET/CT with PCa Nomograms(ERSPC-RC and PCPT-RC)in detection of PCa.Therefore,the purpose of the present study was to assess the diagnostic performance of 68Ga-PSMA PET/CT in the detection of suspected treatment-na?ve PCa,to compare its efficacy with that of the ERSPC-RC and PCPTRC Nomograms in avoiding unnecessary biopsies,and to determine the significant factors leading to performance discrepancies among the three diagnostic tests.Aims:1.To assess the diagnostic performance of 68Ga-PSMA PET/CT in detecting suspected PCa2.To compare the performance of 68Ga-PSMA PET/CT with two cancer-predicting Nomograms in detecting suspected PCa and reducing unnecessary biopsy.3.To explore the reasons leading to the performance discrepancies between 68Ga-PSMA PET/CT and the two Nomograms and to improve the diagnostic accuracy of PCa.Methods:1.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 68Ga-PSMA PET/CT and histopathologic examinations from April 2017 to April 2018 in a large tertiary care hospital in China.The 68Ga-PSMA PET/CT results(PCa or benignancy)were evaluated by two experienced nuclear medicine specialists.2.The risk of positive PCa was evaluated using ERSPC and PCPT Nomograms.The diagnostic performances of 68Ga-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:1.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 68Ga-PSMA PET/CT were 91.67,81.82,89.19,and 85.71%,respectively,in per-patient analyses.2.The AUC of 68Ga-PSMA PET/CT(0.867)was higher than those of ERSPC-RC(0.855)and PCPT-RC(0.770).The net benefit of 68Ga-PSMA PET/CT was greatest for patients within threshold probabilities of 15-90%.Among the 58 patients,11(19%)biopsies suggested by ERSPC-RC were unnecessary and could have been avoided if judged by the 68Ga-PSMA PET/CT results.3.Multivariate analysis revealed that the maximum standardised uptake value(SUVmax)and prostate volume were significant predictive factors for positive PCa results.4.The reasons for the false-negative results of 68Ga-PSMA PET/CT were small size of the tumor or extremely low expression of PSMA.The reason for false positives was overexpression of PSMA in benign prostatic cellsConclusion:1.In suspected PCa patients with tPSA of 0.4-50 ng/mL,68Ga-PSMA PET/CT outperformed the Nomograms in predicting cancer and reducing unnecessary biopsies.2.The risk of PCa was positively correlated with a higher SUVmax and lower prostate volume,which could help clinicians in making preliminary estimates of individual cancer risk and making biopsy decisions in daily medical practice.3.Positive 68Ga-PSMA PET/CT result with overly large prostate volume deserves additional attention because it presumably is false positive. |
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