Aims: FDG uptake in NSCLC is related to glucose transporter type 1 (Glut-1) expression. Here, we investigated the direct causal relationship between FDG uptake and Glut-1 expression to determine the role of Glut-1 in FDG uptake by malignant and benign lymph nodes (LNs).
Methods: Fifty-five curative lung resections in 53 NSCLC patients (male:female=36:17, age=62.0+/-11.8 years) were included. Maximum standardized uptake values (maxSUVs) of LNs in preoperative whole body FDG-PET and Glut-1 immunostaining results were compared.
Results: Of 316 pathologically confirmed LNs, 12.3% (39/316) were malignant, and in malignant LNs, FDG positive LNs were no different from FDG negative LNs in terms of size (15.0+/-6.7 mm vs 10.0+/-6.1mm, p>0.05), or in terms of the proportion of LNs occupied by tumor (60.0+/-28.8% vs 39.2+/-38.4%, p>0.05), but had greater percentages of Glut-1 positive cells in tumors (74.1+/-31.8% vs 22.7+/-18.7%, p<0.01), and Glut-1 staining intensities (3.4+/-0.9 vs 1.8+/-1.3, p<0.01). FDG negative malignant LNs featured cytoplasmic Glut-1 expression and adenocarcinoma. Glut-1 staining intensities were found to be significantly correlated with the maxSUVs of malignant LNs (rho=0.516, p<0.05), but the percentages of Glut-1 positive cells in tumors were not (r=0.2072, p>0.05). Analysis of FDG positive benign LNs showed that maxSUV was not correlated with degree of follicular hyperplasia, or Glut-1 expression (p>0.05).
Conclusions: Intense Glut-1 immunoreactivity was found to be proportionally related to the degree of FDG uptake by malignant LNs in NSCLC. However, the finding that Glut-1 expression in lymphoid hyperplasia showed no correlation with FDG uptake in benign LNs requires further investigation.