Metabolic Characteristics and Diagnostic Contribution of (18)F-FDG PET/CT in Gastric Carcinomas

OBJECTIVES: The aim of this study was to evaluate (18)F-fluoro-2-deoxy-glucose (FDG) uptake patterns in primary tumors and metastatic lesions, and also to assess the diagnostic contribution of positron emission tomography/computed tomography (PET/CT) in the initial staging of gastric cancer (GC). METHODS: The total number of 341 patients with GC were included in this study. All (18)F-FDG PET/CT imagings were performed for initial staging. The maximum standardized uptake value (SUV(max)) of primary tumor, obtained from (18)F-FDG PET/CT imaging was compared between subtypes of GC. RESULTS: Mean SUV(max) of 339 patients’ primary tumor was 12.9±8.6. The highest mean SUV(max) was detected in patients with medullary subtype GC (17.8±9.9) while the lowest mean SUV(max) (9.7±7.6) was seen in signet ring cell carcinoma (SRCC). The primary mean SUV(max) was found statistically higher in tubular adenocarcinoma (TAC) group than SRCC group (p<0.001). Higher SUV(max) values were found statistically significantly correlated with advanced age (aged ≥60) and increased tumor size (>3 cm) in patients with TAC (p=0.03). Primary tumor SUV(max) was found statistically higher in regional lymph node (RLN) positive patients than in RLN negative patients in TAC and SRCC groups (p<0.001 and p=0.012, respectivelly). Also, in patients with SRCC, SUV(max) was significantly higher in the distant metastatic group than in the group without metastasis (p=0.025). CONCLUSION: Increased primary tumor SUV(max) was associated with some of clinical parameters such as age and RLN metastasis in patients with TAC. However, there was no relationship between distant metastatic state and primary tumor (18)F-FDG uptake in TAC. However, high SUV(max) of primary tumor in SRCC was associated with regional and distant metastasis, and primary tumor (18)F-FDG uptake may be a prognostic value for this subgroup.