Our results also indicate that GLUT1 expression in non-intestinal cancers was lower than in intestinal cancers. However, the reason why such aggressive cancers showed low GLUT1 expression is unknown. A previous study found that glutamine metabolism is upregulated in gastric cancer [32]. Gastric cancer cells use glutamine as an energy

source in a hypoxic tumor microenvironment, which may eliminate the necessity for glucose transport. This metabolic alteration accompanied with malignant transformation has been reported in other cancers [33]. Interestingly, a glutamine-based PET is being developed; if this website successful, this contradiction could be disproved in the future. On the other hand, HIF1α expression correlated with SUV in both

types, although a more significant correlation was seen in non-intestinal specimens. The non-intestinal tumors may have been influenced Pifithrin-�� nmr more by hypoxia derived from tumor fibrosis due to a scattering tumor growth pattern than hypoxia due to Oligomycin A increased tumor size. Further research will be needed to determine the exact reason. Limitations of this study There are several limitations in our study. First, we examined 50 cases of gastric cancer patients. The fewness of cases affects the statistical analysis and makes it difficult to get firm results in association of FDG uptake and the expression of the proteins. Second, we could not exclude the possibility of contribution of physiological FDG uptake in normal stomach on cancerous lesion. Finally, our results did not show the direct physiological relationship between HIF1α as a marker of hypoxic condition and FDG accumulation. Conclusions The usefulness of FDG-PET in the detection of malignant tumors or prediction of prognoses has been widely reported. However, our results indicate that the degree of FDG accumulation does not always suggest a prognosis in gastric cancer. This study is the first to show the

correlation by evaluating FDG uptake for in a quantitative manner. Upregulation of glucose transport due to increased GLUT1 expression was not an explanation for the different FDG uptakes observed, although tumor hypoxia and HIF1α expression may provide a reasonable mechanism. Further investigation is needed to confirm these results, but metabolic alternation through HIF1α induction in tumor hypoxia could increase FDG uptake in gastric cancer. Acknowledgements We are extremely grateful to all the clinical staff who cared for these patients. We also are thankful to Dr. Shoji Kimura for his reliable experimental suggestion. References 1. Shimada H, Okazumi S, Koyama M, Murakami K: Japanese gastric cancer association task force for research promotion: clinical utility of 18 F-fluoro-2-deoxyglucose positron emission tomography in gastric cancer. A systematic review of the literature. Gastric Cancer 2011, 14:13–21.PubMedCrossRef 2. Murakami K: FDG-PET for Hepatobiliary and pancreatic cancer: advances and current limitations.