Correlations between selected tumor markers and fluorodeoxyglucose maximal standardized uptake values in esophageal cancer.

OBJECTIVE: Esophageal cancer tumor biology is best assessed clinically by 2-[18F]fluoro-2-deoxy-d-glucose (FDG)-PET. Both FDG-PET maximal positron emission tomography (PET) standardized uptake values (SUVmax) and selected tumor markers have been shown to correlate with stage, nodal disease, and survival in esophageal cancer. Interestingly, there is limited data examining the relationship between FDG-PET SUVmax and expression of these tumor markers in esophageal cancer. The purpose of this study was to determine the correlation of tumor markers with FDG-PET SUVmax in esophageal cancer.
METHODS: FDG-PET SUVmax was calculated in 67 patients with esophageal cancer of which 59 (88%) had adenocarcinoma. Neoadjuvant radiotherapy and/or chemotherapy were administered to 42% (28/67) of patients. Esophageal tumor tissue and surrounding normal tissue was obtained and tissue microarrays were created. Immunohistochemical analysis was performed for five known esophageal cancer tumor markers (GLUT-1, p53, cyclin D1, epidermal growth factor receptor (EGFR), and vascular endothelial growth factor (VEGF)). Assessment of each tumor marker was made by two independent, blinded pathologists using common grading criteria of intensity and percentage of cells stained. A p value <0.05 was considered significant.
RESULTS: There were 55 men (82%) and 12 women (18%) with a median age of 63 years (range 40-83). Pathologic staging included stage I (n=29, 43%), stage II (n=19, 28%), stage III disease (n=18, 27%), and stage IV disease (n=1, 2%). PET SUVmax correlated with T stage (p=0.001). In patients undergoing surgery without induction therapy, increasing SUVmax values correlated with increased expression of GLUT-1 transporter (p=0.01). There was no correlation between SUVmax and EGFR, cyclin D1, VEGF, or p53 expression in primary tumor.
CONCLUSIONS: FDG-PET SUVmax correlates with an increased expression of GLUT-1 transporter in esophageal cancer specimens not subjected to induction therapy. No significant difference in tumor marker expression was noted between patients undergoing induction therapy or surgery alone except p53 expression decreased in primary tumors following induction therapy. Failure of SUVmax values to correlate with known prognostic esophageal cancer tumor markers suggests that FDG-PET may have limited clinical utility in assessing response to therapies targeting these markers.