۶۸Ga-FAPI PET/CT in diagnosis, staging and management of Gastric Carcinoma: A systematic review and meta-analysis

Objective(s): Gastric carcinoma is a major cause of cancer related mortality worldwide. Accurate staging, including detection of nodal and distant metastases, is essential for treatment planning. Conventional ۱۸F-FDG PET/CT has important limitations in gastric cancer, especially in diffuse and mucinous histologic subtypes. Fibroblast activation protein inhibitor (FAPI) PET/CT targets cancer-associated fibroblasts and may improve lesion conspicuity.To systematically review and meta-analyse the diagnostic performance of ۶۸Ga-FAPI PET/CT for staging of gastric carcinoma and, in studies with head-to-head data, to compare it with ۱۸FFDG PET/CT. Methods: This review followed PRISMA ۲۰۲۰ recommendations. The protocol was prospectively registered in PROSPERO (CRD۴۲۰۲۵۱۰۵۶۹۷۶). PubMed, EMBASE, Web of Science and Cochrane libraries were searched from January ۲۰۱۶ to December ۲۰۲۳ for clinical studies evaluating ۶۸Ga-FAPI PET/CT in histologically confirmed gastric carcinoma. Two reviewers independently screened records, extracted data, and assessed risk of bias using QUADAS-۲. For ۶۸Ga-FAPI PET/CT, per patient ۲×۲ tables were constructed for detection of primary tumors and metastatic sites. Pooled sensitivity, specificity, positive and negative predictive values and accuracy were estimated using random effects models. Summary ROC (SROC) and hierarchical SROC (HSROC) curves were generated. Comparative analyses with ۱۸F-FDG PET/CT were restricted to studies with head to head data in the same patient cohort, and areas under the curve (AUCs) were compared with DeLong’s test. Results: Fourteen studies (۶۶۱ patients) were included; nine provided head to head comparisons with ۱۸F-FDG PET/CT. For detection of primary gastric carcinoma with ۶۸Ga-FAPI PET/CT, pooled sensitivity and specificity were ۹۵-۹۶% and ۹۳% respectively, with an AUC of ۰.۹۶ (۹۵% CI ~ ۰.۸۹-۱.۰۰). For metastatic disease, pooled accuracy for lymph node, omental, visceral and skeletal metastases ranged from ~۸۹% to ۹۷%. In head to head studies, ۶۸Ga-FAPI PET/CT showed higher AUCs than ۱۸F-FDG PET/CT for primary tumors (۰.۹۶ vs ۰.۷۶; p=۰.۰۰۱) and omental metastases (۰.۹۷ vs ۰.۷۸; p=۲.۶×۱۰⁻⁵). Heterogeneity was moderate for most outcomes. Funnel plots and trim and fill analyses suggested possible small study effects, but adjusted pooled diagnostic odds ratios remained high. Conclusions: ۶۸Ga-FAPI PET/CT demonstrates high diagnostic accuracy for staging of gastric carcinoma and appears to outperform ۱۸F-FDG PET/CT in many settings, particularly for omental and some visceral metastases and for histologic subtypes with low FDG avidity. These findings support the use of ۶۸Ga-FAPI PET/CT as a promising complementary imaging modality for staging and restaging, but not as a stand-alone diagnostic test. Larger, prospective multicentre studies with standardized protocols are required before routine guideline incorporation.

کلیدواژه ها:

Gastric carcinoma ، ۶۸Ga-FAPI ، PET/CT ، Fibroblast activation protein ، Staging ، Meta-analysis