FDG uptake, GLUT-1 glucose transporter and cellularity in human pancreatic tumors.
We previously reported that grading of GLUT-1 glucose transporter expression was related closely to FDG accumulation in FDG PET in human cancers. But in this strong GLUT-1 expression group, there was an enormous range of standardized uptake values (SUVs) within them.


METHODS
To evaluate other factors determining the FDG PET uptake, FDG PET was performed in 36 preoperative patients (mean age 62.0 yr) suspected of having pancreatic tumors, including 33 malignant and 3 benign neoplastic tumors. FDG uptake at 50 min after injection of 185 MBq 18F-FDG with > 5 hr fasting condition was semiquantitatively analyzed as SUVs. The GLUT-1 expression was studied by immunohistochemistry of paraffin sections from these tumors after the operation using the antiGLUT-1 antibody. The number of tumor cells within a 5- x 5-mm square was counted manually using x200 magnification photographs and was graded immunohistochemically as strong, weak or negative.


RESULTS
In all 36 cases there were 3 cases of GLUT-1 negative, 8 of GLUT-1 weak positive and 25 of GLUT-1 strong positive. In all cases, the total number of tumor cells had no significant value for SUVs. Among 33 GLUT-1 positive cases, the number of GLUT-1 positive tumor cells correlated significantly with SUVs (p < 0.01). Only in 25 strong grade cases, the number of GLUT-1 strong positive tumor cells had a more significant value for SUVs (p < 0.005). Computational multivariate analysis using multiple regression for SUVs was performed evaluating the five variables as follows: tumor size, GLUT-1 immunohistochemical grading, number of total tumor cells, number of total GLUT-1 positive tumor cells and number of GLUT-1 strong positive cells. This analysis revealed that only the variable, the number of GLUT-1 strong positive cells, had a significant regression coefficient for SUVs (standard regression coefficient = 0.855, p < 0.0001).


CONCLUSIONS
These data indicate that GLUT-1 expression plays an essential role in higher FDG accumulation in pancreatic tumor FDG PET, and the cellularity has a significant influence on SUVs only in the condition of GLUT-1 strong positive expression.
Department of Nuclear Medicine, Kyoto University Faculty of Medicine, Japan.
T
T
Higashi
N
N
Tamaki
T
T
Torizuka
Y
Y
Nakamoto
H
H
Sakahara
T
T
Kimura
T
T
Honda
T
T
Inokuma
S
S
Katsushima
G
G
Ohshio
M
M
Imamura
J
J
Konishi
D000230:Adenocarcinoma / Q000000981:diagnostic imaging / Q000378:metabolism / Q000473:pathology; D005260:Female; D005462:Fluorine Radioisotopes; D019788:Fluorodeoxyglucose F18 / Q000493:pharmacokinetics; D051272:Glucose Transporter Type 1; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008875:Middle Aged; D009004:Monosaccharide Transport Proteins / Q000032:analysis*; D010179:Pancreas / Q000378:metabolism / Q000473:pathology; D010190:Pancreatic Neoplasms / Q000000981:diagnostic imaging* / Q000378:metabolism / Q000473:pathology; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics; D014055:Tomography, Emission-Computed
D005462:Fluorine Radioisotopes; D051272:Glucose Transporter Type 1; D009004:Monosaccharide Transport Proteins; D019275:Radiopharmaceuticals; C495677:SLC2A1 protein, human; D019788:Fluorodeoxyglucose F18