Peculiar cases of a \"sleeping\" brain in alert cancer patients

Abstract

Cognitive and constitutional symptomatology is common in cancer patients but the causes are not well understood. To investigate whether cancers cause these symptoms by changing cerebral metabolism, we measured the cerebral rate of glucose consumption (CMRglc) in patients diagnosed with a lung lesion.\n\nMethodsThe CMRglc was quantified in 20 patients undergoing 18F-FDG PET for lesion staging. The cognitive status was assessed by neuropsychological testing.\n\nResultsParadoxically, despite being alert three of the patients had CMRglc typical of people who are in deep sleep or anesthetized. All three had cancers, two died within 2 months of scanning. Remaining patients including four with early stage cancer had CMRglc within normal range.\n\nConclusionsWe speculate that the low CMRglc reflects a switch to an alternative energy source that is mediated by cancers remotely. Identifying the underlying mechanism and the alternative energy sources may help to understand how cancers can change body metabolism.