Influence of cell proportions and proliferation rates on FDG uptake in squamous-cell esophageal carcinoma: A PET study

Purpose: We investigated the influence of cell proportions and proliferation activities on tumor maximum standard uptake value (SUV(max)) in patients with squamous-cell esophageal cancer (SCEC). Methods: Sixteen (16) patients with untreated SCEC were examined with (18)F-flourodeoxyglucose positron emission tomography (FDG-PET). The tumor SUV(max) were calculated. Tumors were resected by transthoracic esophagectomy. Tissues were stained with hematoxylin and eosin for the measurement of cell proportions and MIB-1 for measurement of proliferation indices (PIs). Tumor SUV and histologic data were related by using multiple linear regression analysis. Results: The mean proportion of tumor cells in the tumor site was 58.1% (+/- 12.1%); the proportion of inflammatory cells was 34.2% (+/- 14.2%); the PI of tumor cells was 70.5% (+/- 11.8%); and the PI of inflammatory cells was 22.2% (+/- 7.6%). The tumor PI was the only variable that was significantly associated with the FDG uptake in the tumor site (p=0.04). The correlation was low (Pearson-coefficient Gamma=0.51). The Pearson-correlation-coefficient between tumor SUV and the fraction of inflammatory cells was Gamma=0.37 and between tumor SUV and PI of inflammatory cells Gamma=0.13. Conclusions: In untreated SCEC-patients, the tumor maximum FDG uptake is weakly associated with the proliferation rate of tumor cells. In contrast, neither the proportion nor the PI of inflammatory cells in the tumor site significantly correlates with the maximum SUV and should not profoundly affect PET interpretations.