High FDG uptake in PET/CT predicts worse prognosis in patients with metastatic gastric adenocarcinoma

Abstract

Purpose: We evaluated the role of FDG-PET/CT in patients with metastatic gastric adenocarcinoma before palliative chemotherapy to predict prognosis and chemotherapeutic response.

Methods: The study included 35 consecutive newly diagnosed patients with metastatic gastric adenocarcinoma who underwent FDG-PET/CT before palliative chemotherapy. Maximum standardized uptake value (SUVmax) of the primary tumor was assessed to evaluate survival and chemotherapeutic response. Survival analysis was performed for time to progression and overall survival using the Kaplan-Meier method. Cox proportional hazard models were used to determine independent prognostic factors.

Results: All primary tumors were visualized using FDG-PET/CT (mean SUVmax = 8.1 ± 4.5, range 2.5-22.1). Sensitivity, specificity, and accuracy of FDG-PET/CT in detection of solid organ metastasis were 95.2% (20/21), 100% (14/14), and 97.1% (34/35), respectively. No significant difference of primary tumor SUVmax was found among the chemotherapeutic response groups. Univariate survival analysis demonstrated ECOG performance status (≥2), presence of solid organ metastasis, number of organs involved in distant metastasis (≥2), and SUVmax of the primary tumor (>8) as significant predictors for poor overall survival. Multivariate survival analysis showed SUVmax of the primary tumor (P = 0.048), presence of solid organ metastasis (P = 0.015), and ECOG performance status (P = 0.002) as significant independent prognostic predictors for overall survival.

Conclusions: High FDG uptake of the primary tumor in patients with metastatic gastric adenocarcinoma is associated with poor overall survival. Assessment of tumor FDG uptake has limited value for prediction of chemotherapeutic response, but provides useful information regarding prognosis.

Fig. 1

Flowchart shows patient selection in study

Fig. 2

Correlation between SUVmax of primary tumors and distant metastatic sites

Fig. 3

Kaplan–Meier analysis of overall survival of patients with metastatic gastric adenocarcinoma according to SUVmax of the primary tumor

Fig. 4

FDG-PET/CT and contrast-enhanced CT of patients with metastatic gastric adenocarcinoma. a 55-year-old man with high SUVmax of the primary tumor (18.2, arrow). Overall survival was 8.4 mo. b 67-year-old man with low SUVmax of the primary tumor (4.5, arrow). Overall survival was 21.9 mo