Detection rate of gastrin-releasing peptide receptor (GRPr) targeted tracers for positron emission tomography (PET) imaging in primary prostate cancer: a systematic review and meta-analysis

The gastrin-releasing peptide receptor (GRPr) has gained recognition as a promising target for both diagnostic and therapeutic applications in a variety of human cancers. This study aims to explore the primary tumor detection capabilities of [⁶⁸Ga] Ga-GRPr PET imaging, specifically in newly diagnosed intra-prostatic prostate cancer lesions (PCa). Following PRISMA-DTA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses of Diagnostic Test Accuracy Studies) guidelines, a systematic literature search was conducted using the Medline, Embase, Scopus, and Web of Science databases. Data regarding patient characteristics and imaging procedure details—including the type of radiotracer used, administered activity, image acquisition time, scanner modality, criteria, and detection rate of index test—were extracted from the included studies. The pooled patient-and lesion-based detection rates, along with their corresponding 95% confidence intervals (CI), were calculated using a random effects model. The final analysis included 9 studies involving 291 patients and 350 intra-prostatic lesions with [⁶⁸Ga] Ga-GRPr PET imaging in primary PCa. In per-patient-based analysis of [⁶⁸Ga] Ga-GRPr PET imaging, the pooled detection rates of overall and patients with Gleason score ≥ 7 were 87.09% (95% CI 74.98–93.82) and 89.01% (95% CI 68.17–96.84), respectively. In per-lesion-based analysis, the pooled detection rate [⁶⁸Ga] Ga-GRPr PET imaging was 78.54% (95% CI 69.8–85.29). The pooled detection rate mpMRI (multiparametric magnetic resonance imaging) in patient-based analysis was 91.85% (95% CI 80.12–96.92). The difference between the detection rates of the mpMRI and [⁶⁸Ga] Ga-GRPr PET imaging was not statistically significant (OR 0.90, 95% CI 0.23–3.51). Our findings suggest that [⁶⁸Ga] Ga-GRPr PET imaging has the potential as a diagnostic target for primary PCa. Future research is needed to determine the effectiveness of [⁶⁸Ga] Ga-GRPr PET in delivering additional imaging data and guiding therapeutic decisions.