When stratified by tumor histology, the association between the GLUT3 rs7309332C>T and OS/DFS was not limited to either squamous cell carcinoma (SCC) or adenocarcinoma (AC), although the significant association remained only in AC for OS (P = 0.40 for SCC and P = 0.04 for OS) and only in SCC for DFS (P = 0.03 for SCC and P = 0.08 for OS).
AC and SCC showed a high positive expression rate for both Glut-1 and Glut-3, although the degree of overexpression was significantly higher in SCC than AC.
The present study supports the hypothesis that tumor cell differentiation in combination with overexpression of GLUT-1 and GLUT-3 determine the extent of FDG accumulation and that squamous cell carcinomas accumulate more FDG than adenocarcinomas or large cell carcinomas.
The signals for GLUT1 and GLUT3 mRNAs varied markedly throughout the SCC tumor population but no clear relationship with the grade of differentiation was found.