Application Of ⁶⁸Ga-PSMA PET/CT For The Detection Of Distant Metastases In Patients With Newly Diagnosed Prostate Cancer

Objectives1.To compare the differences for the detection of bone metastases between⁶⁸Ga-PSMA PET/CT and radionuclide bone scintigraphy in patients with newly diagnosed prostate cancer.2.To preliminarily explore the best time point in the application of ⁶⁸Ga-PSMA PET/CT for distant metastases of newly diagnosed prostate cancer.Methods1.The clinical data of 75 patients with newly diagnosed prostate cancer who underwent ⁶⁸Ga-PSMA PET/CT and radionuclide bone scintigraphy during June 2017 and September 2018 were retrospectively reviewed.According to the clinical diagnosis,the patients were divided into bone metastasis group and non-bone metastasis group.Sensitivity,specificity,positive predictive value and negative predictive value of the two examinations for the diagnosis of bone metastasis were calculated respectively.The AUC value was calculated to compare the diagnostic efficiency of the two examinations.Bone metastasis grading of the two examinations was compared through the Wilcoxon rank testing.2.The clinical data of 74 patients with newly diagnosed prostate cancer who had showed PSMA-positive lesions on ⁶⁸Ga-PSMA images during May 2017 and January2019 were retrospectively reviewed.According to the presence of metastases and metastatic sites,the patients were divided into 5 groups:non-metastatic prostate cancer group,non-regional lymph node metastasis group,bone metastasis group,non-regional lymph node metastasis+bone metastasis group and visceral metastasis group.The distant metastases detected by ⁶⁸Ga-PSMA PET/CT were statistically analyzed with the onset age,prostate-specific antigen?PSA?levels,Gleason scores,grading groups,T stage and N stage.Results1.Among the 75 patients with newly diagnosed prostate cancer,42 patients?56%?had no bone metastases and 33 patients?44%?had bone metastases.Based on patients,the sensitivity,specificity,positive predictive value and negative predictive value for⁶⁸Ga-PSMA PET/CT and radionuclide bone scintigraphy were 100%vs.87.88%,97.62%vs.92.86%,97.06%vs.90.63%and 100%vs.90.70%,respectively.There was significant difference in AUC value between the two examinations?0.988 vs.0.904,P=0.0112?.Two examinations exhibited significantly different bone metastases grading?Z=-3.275.P=0.001?.2.The ⁶⁸Ga-PSMA PET/CT revealed 42 patients?56.8%?without distant metastatic lesions and 32 patients?43.2%?with distant metastatic lesions.Compared with patients without distant metastases,patients with distant metastases had significantly higher PSA,Gleason score,grading groups and T stage,and greater involvement of regional lymph nodes.The differences were statistically significant?P<0.001?.However,There was no difference in the age of onset between patients with and without distant metastases?P=0.461?.The PSA level,Gleason score,grading groups,T stage and N stage were positively correlated with the metastatic degree in the 5 groups?P<0.0001?,respectively.Multivariate linear regression analysis indicated that PSA level,ISUP classification and N staging contributed to the degree of metastasis,and PSA level contributed the most?t=6.582,P<0.001?.PSA?36ng/mL might indicate the occurrence of distant metastases.Conclusions1.Compared with radionuclide bone scan,⁶⁸Ga-PSMA PET/CT has higher diagnostic efficiency in detecting bone metastases of prostate cancer,and can detect soft tissue metastases and more bone metastases.2.⁶⁸Ga-PSMA PET/CT can be recommended to detect distant metastatic lesions of newly diagnosed prostate cancer patients with grading groups 4⁵,N stage 1,especially PSA?36 ng/mL,in order for precise staging and appropriate individualized treatment.