Variable 18F-fluorodeoxyglucose uptake in gastric cancer is associated with different levels of GLUT-1 expression

Objectives Detection rates of gastric cancer in F-18-fluorodeoxyglucose (FDG)-PET depend on the histopathological characteristics of the primary tumor. To clarify this observation, FDG uptake in gastric carcinoma was analyzed by focusing on histopathology and on the expression of the glucose transporter (GLUT-1) in the primary tumor. Methods Thirty-five patients with the diagnosis of gastric cancer underwent FDG-PET with visual image analysis and measurement of maximum standardized uptake value (SUVmax) before surgical treatment. Resected tumor samples were categorized according to Union internationale contre le cancer, WHO, and Lauren classification and tumor differentiation. GLUT-1 expression was graded semiquantitatively by immunohistochemistry. Statistical analysis was done for the correlation of histology, different classifications, and tumor grading with SUVmax and GLUT-1 expression. Results SUVmax significantly correlated with histopathological classifications according to the WHO (P=0.009) and Lauren classification (P=0.034). Signet-ring cell carcinoma had a median SUVmax of only 3.0 (range, 1.0-11.5). Median SUVmax for papillary and tubular carcinoma was 7.8 (range, 1.8-14.4). In 21 (60%) cases, GLUT-1 expression in the primary tumor was positive. GLUT-1 expression correlated significantly with tumor differentiation (P=0.018) and the classification according to Lauren (P=0.023) and WHO (P<0.001). Thirteen (76%) of 17 signet-ring cell carcinoma cases did not show any GLUT-1 expression. SUVmax in relation to GLUT-1 expression showed a significant correlation (P=0.002). For cases with detectable GLUT-1 expression the median SUVmax was 6.9 (range, 2.3-14.1) versus a median of 3.1 (range, 1-8.8) for cases without GLUT-1 expression. Conclusion FDG uptake in gastric cancer depends on GLUT-1 expression. One major reason for low FDG uptake in signet-ring cell carcinoma is the low GLUT-1 expression in this histological subtype of gastric cancer. Nucl Med Commun 31: 532-538 (C) 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins.