To our knowledge, this is the first meta-analysis ofthediagnostic efficacy for 68Ga-PSMA PET/CT in aprostatecancer patient with pelvic LN metastasis risk. We foundthat theindicators and results of 68Ga-PSMA PET/CT showasatisfactory diagnostic efficacy.
In previous treatments, LN staging of prostate cancerpatientscan only be determined by performing PLND according tothesituation during the operation. However, this method is notalwaysfeasible [24].Clinically, the use of PLND is not alwaysfeasible, beingrestricted for the following reasons: not everypatient willreceive PLND, limited anatomical locations performed,andconsideration regardingcomplications[25–27], resulting in suboptimal lymphnodestaging. 68 Ga-PSMA PET/CT is a more accurate methodtodetermine the LN stage of PCa patientsbeforesurgery[28],which can be incorporated into clinicalpractice.
Our meta-analysis included 10 studies from differentcountriesand regions, involving a total of 701 patients. Thepooledspecificity of 0.95 (95% CI: 0.87–0.98) for68Ga-PSMAPET/CT. But pooled sensitivity was recorded as0.84 (95% CI:0.55–0.95), which is not enough to convince us to giveup theremaining 20% of the patient. The Youden index was 0.79. AUCwas0.97 (95% CI: 0.95–0.98), which was in line with ourinitialpredictions. Through these comprehensive indicators, we canthinkthat 68Ga-PSMA PET/CT has better diagnosticefficacy inpreoperative LN staging in patients with prostatecancer. In thepast few decades, CT and MRI have been used todetermine the LNstaging before radical prostatectomy, but theiraccuracy rate isstill low compared to the goldstandard[6].Hovels et al. Performed ameta-analysis of 24 studies to assessCT/MRI for preoperativeevaluation of LN staging. In his research,for CT, pooledsensitivity and specificity was 0.42 (95% CI:0.26–0.56) and 0.82(95% CI: 0.8–0.83) respectively. For MRI, pooledsensitivity andspecificity was 0.39 (95% CI: 0.22–0.56) and 0.82(95% CI:0.79–0.83)[29].From this point of view, the performanceof CT and MRI in judgingLN staging is not satisfactory. Ifclinicians rely on CT or MRI,they will easily make the wrongdecision on the patient’scondition. In our analysis, we could seethat two studies havelower sensitivity, 0.38(95%: 0.28–0.48) and0.33 (95% CI:0.24–0.43) respectively[10, 22]. The reason for this analysis was that,dueto the technical level of the test, the sample size, andbiasbetween the samples, it might have lead to different finalresults.The specificity value provided in one study issignificantlylower[17]. Wethought that the main reason is thatthe patients included inHerlemann’s[17]study received different PLNDs. Among them,20 received primaryPLND and 14 received secondary PLND, which maybe the main reasonfor the lower specificity. Multi-parametermagnetic resonance(mpMR) also plays a large role in thepreoperative evaluation ofprostate cancer, especially in judgingextraprostatic extension(EPE) of the tumor, invasion of the seminalvesicle(SVI)[20]. In aretrospective study by Van Leeuwen atal. They also compared thediagnostic accuracy of mpMR and68Ga-PSMA PET/CT for LNmetastasis in a patient withintermediate high-risk PCa. Thesensitivity was 14% and 53%,respectively, and the specificity was99% and 88%,respectively[2].All of these indicated that68 Ga-PSMA PET / CT has betterdiagnostic efficacy and wasexpected to be popularized and used inclinical.
The higher the value of DOR, the better the diagnostic valueofthis diagnostic method. In our study, The DOR value was 4.60(95%CI: 2.91–6.30), indicating that the overall accuracy washigh.Pooled PLR and NLR value was 17.19 (95% CI: 6.27–47.17) and0.17(95% CI: 0.05–0.56), respectively. This can be understood astheprobability of 68Ga-PSMA PET/CT correctly judgingLNmetastasis is 17 times that of misjudging, and the probabilityofcorrectly judging LN non-metastasis is 0.17 times thatofmisjudging. At the same time, we also noticed that thepublicationbias shown by Deek’s funnel plot (Fig. 5) has a P-value of 0.02. Itisunderstandable that most of the articles we includedwereretrospective trials and were not included in relatedstudiesbefore 2016, which led to the results. From the dataresults, it isworth trying to use 68 Ga-PSMA PET / CT todiagnose LN stagingin patients with PCa.
We perform this meta-analysis strictly according toPRISMguidelines[30].However, there are still some limitationsin our meta-analysis.First, most of the studies we included weresingle-centerretrospective studies, and the existence of selectionbias mayaffect our judgment. Second, the sample populationsincluded inthese articles are only Asia, Europe, and Australia, sopopulationbias is unavoidable. Third, the sample size is too small.Due tothe clinical application of 68Ga-PSMA PET/CT inthefuture, there is not a sufficiently large sample size tobeincluded in our meta-analysis. Compared with PLND,although68Ga-PSMA PET/CT has only moderate sensitivityandbetter specificity, it can perform relatively accurate LNstagingof detected PCa patients. At this point,68Ga-PSMAPET/CT is due to any other imagingexaminations, but due to manylimitations, our conclusions stillrequire a larger sample size,multi-center prospective randomizedcontrolled trial to verify.