Predictive value of F-FDG PET/CT metabolic parameters for gastric cancer patients' microsatellite instability status.

[BACKGROUND] This study is to investigate the feasibility of using the F fluorodeoxyglucose (F-FDG) positron emission tomography / computed tomography (PET/CT) metabolic parameters to predict the MSI status of gastric cancer (GC) patients.

[MATERIALS AND METHODS] Patients with GC who underwent F-FDG PET/CT before surgery from January 2021 to June 2022 were retrospectively analyzed. Calculate and record the F-FDG PET/CT metabolic parameters of primary gastric cancer lesions, including maximum, peak and average standardized uptake values (SUVmax, SUVpeak, and SUVmean), as well as metabolic tumor volume (MTV) and total lesion glycolysis (TLG). The status of MSI was determined by immunohistochemical assay. The differences of quantitative parameters between MSI and microsatellite stability (MSS) groups were evaluated, and the prediction performance of metabolic parameters was analyzed by using subject operating characteristic (ROC) analysis and area under ROC curve (AUC).

[RESULTS] 62 patients (44 males and 18 females; age range 30-81 years-old, median age 65.5 years-old) were finally included. There were 20 patients in MSI group and 42 patients in MSS group. MTV, MTV, MTV and MTV, as well as TLG showed significant differences between the two groups (all P values <0.05), within which MTV demonstrated the highest AUC value [0.825, 95% confidence interval (CI): 0.703-0.947] in predicting MSI, the cutoff value was 44.1. The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy value were 66.7%, 97.6%, 86.7%, 85.1%, and 85.5%, respectively. In multiple logistic regression analysis, MTV was an important predictor of MSI.

[CONCLUSION] F-FDG PET/CT metabolic parameters could predict the preoperative GC MSI status, and MTVshows the highest predictive efficiency. F-FDG PET/CT imaging might be used as a non-invasive tool to guide the immunotherapy and individualized treatment of GC patients.