Hypometabolism in the limbic system of cancer patients observed by positron emission tomography

Brain images obtained by a positron emission tomography with 18F-fluorodeoxyglucose from 19 pretreatment cancer patients with variable cancers except brain cancers were compared with those from 17 inpatients with benign diseases. Relative reduction in regional cerebral metabolism of glucose was found mainly in the limbic structures including the bilateral orbitofrontal cortex, lateral frontal cortex, cingulate gyrus, thalamus, hippocampus and parahippocampal gyrus, insulae, and basal ganglia. The regional metabolism tended to be low in the patients who had severe pains which required opiates and morphines, and tended to be preserved in the patients who were already disclosed of their malignancy based on previous studies such as biopsy. Our findings would support that psychological deficits in cancer patients are associated with abnormalities in regional brain metabolism in the limbic system.