BACKGROUND: The aim of this study was to investigate influences of depressivestates, chemotherapy and existence of remaining tumors on the regional brain activity of cancer patients.
MATERIAL AND METHODS: Positron emission tomography with 18F-fluorodeoxyglucose was performed on 21 patientswith various types of cancer. Their brain images were compared to 10 age- and gender-matched controldata using statistical parametric mapping (SPM). The patients were subgrouped into the with and withoutdepression based on the scores on Zung's self-rating depression scale (SDS), with and without previouschemotherapy, and with and without existence of remaining tumors.
RESULTS: Significant metabolic reductionwas detected in the cingulate gyrus, prefrontal, dorsolateral prefrontal, temporoparietal cortices andbasal ganglia in cancer patients. These findings were close to known lesions of major depression. Intra-groupcomparisons showed that these hypometabolic findings were associated with the depth of depressive state.Influences of chemotherapy and remaining tumors on the cerebral cortex seemed to be weaker than thatof psychological factors.
CONCLUSIONS: The present pilot study suggests that frontal hypoactivity commonlyseen in cancer patients is likely to be associated with depression rather than chemotherapy or remainingtumors. A brain mapping technique might be useful in evaluating neuropsychiatric problems in cancer patients.

Keywords: PET, cerebral glucose metabolism, cancer patient, Depression, chemotherapy, paraneoplastic factor