Abstract
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Objectives: Accurate prediction of risk stratification and metastatic risk of prostate cancer has significant impacts on patient's subsequent treatment plan and disease outcomes. This study was to investigate the value of 68Ga-PSMA-617 PET/CT in predicting risk stratification and metastatic risk of prostate cancer.
Methods: A total of 40 newly diagnosed patients with prostate cancer as confirmed by needle biopsy were continuously included. 68Ga-PSMA-617 PET/CT and clinical data of all patients were retrospectively analyzed. PET images were semi-quantitatively analyzed to obtain maximum standardized uptake value (SUVmax) and volumetric parameters of primary prostate cancer, including intraprostatic PSMA-derived tumor volume (iPSMA-TV) and intraprostatic total lesion PSMA (iTL-PSMA). All patients were simplified into low-medium risk group (PSA≤20 ng/mL, Gleason score 6-7, and cT1-T2c) and high-risk group (PSA > 20 ng/mL, Gleason score 8-10, or cT3-T4) according to the risk stratification criteria of prostate cancer described in NCCN Guideline. Univariate logistic regression models for the assessment of high-risk prostate cancer and metastatic risk were established using the above semi-quantitative parameters of 68Ga-PSMA-617 PET/CT; then the efficacy of these predictive models was assessed.
Results: Totally 30/40 (75%) were diagnosed as high-risk prostate cancer and 10/40 (25%) were low-medium risk prostate cancer. SUVmax, iPSMA-TV and iTL-PSMA were found to be predictive factors useful to distinguish high-risk from low-medium risk prostate cancer (Area under ROC curve was 0.843, 0.802 and 0.900, respectively, all at p <0.05). Metastatic lesions of prostate cancer were detected in 15/40 (38%) patients. Predictive models based on iPSMA-TV and iTL-PSMA as parameters were able to predict the metastatic risk of prostate cancer, the area under ROC curve was 0.863 and 0.848, respectively, both p <0.05. However, predictive model based on SUVmax was unable to predict metastatic risk (p=0.12). Moreover, the SUVmax, iPSMA-TV and iTL-PSMA were found to be correlated with the Gleason score(GS), Spearman correlation coefficient was 0.42, 0.63 and 0.63 respectively, all at p<0.01. In addition, these parameters were also significantly correlated with the prostate-specific antigen (PSA) level, Spearman correlation coefficients was 0.43, 0.60 and 0.65 respectively, all at p<0.01. Conclusions: Semi-quantitative analysis indexes of 68Ga-PSMA-617 PET/CT imaging can be used as an “imaging biomarker” to predict risk stratification and metastatic risk of prostate cancer.