EXPRESSION OF GLUCOSE TRANSPORTERS IN HUMAN PANCREATIC TUMORS COMPARED WITH INCREASED FDG ACCUMULATION IN PET STUDY

Although overexpression of GLUT-1 glucose transporter has already been reported in human cancers, the mechanism of glucose entry into pancre atic cancers remains unknown. To evaluate the relationship between GLU T glucose transporters and FDG uptake, FDG-PET was performed in 34 pre operative patients (mean age, 60.9 yr) with suspected pancreatic tumor s, including 28 malignant and 6 benign tumors. Methods: FDG uptake at 50 min after injection of 185 MBq of [F-18]FDG with >5 hr of fasting w as semiquantitatively analyzed as standardized uptake values (SUVs). T he GLUT expression was studied by immunohistochemistry of paraffin sec tions from these tumors after operation using anti-GLUT-1, -2, -3, -4 and -5 antibodies to obtain immunohistochemical grading (''strong, ''w eak'' and ''negative'') by three experienced physicians. Results: Of 2 6 malignant tumors proved by histological examination, 23 (88%) tumors were positive for the expression of GLUT-I glucose transporter, and 1 7(61%)showed strong expression. On the other hand, 13 (46%), 0 (0%), 9 (36%) and 13 (46%) malignant tumors were positive for the expression of GLUT-2, -3, -4 and -5 glucose transporters, respectively. Three of six benign tumors showed strong GLUT-I expression. Concerning GLUT-2, -3, -4 and -5, only one benign tumor showed positive GLUT-5 expression . Thus, GLUT-I showed relatively high sensitivity but low specificity (50%) for detecting malignant tumors, whereas GLUT-2, -3, -4 and -5 ha d lower sensitivities but higher specificities. Correlations between S UVs and grading of GLUT immunoreactivity were significant in GLUT-1 (s trong, 4.49 +/- 2.95; weak, 3.42 +/- 1.21; negative, 2.52 +/- 0.84) (p < 0.05) but not in the remaining four GLUT transporters. Conclusion: These data indicate that GLUT-I has a significant role in the malignan t glucose metabolism and may contribute to the increased uptake of FDG in PET imaging in patients with pancreatic tumor.