Effects on 18F-FDG PET/CT Brain Glucose Metabolism in Rectal Cancer Patients Undergoing Neoadjuvant Chemotherapy.

PURPOSE: Retrospective study of the effects of anticancer treatment on the brain metabolism of patients diagnosed with rectal cancer based on a large and homogeneous sample of 40 paired F-FDG PET/CT volumes taken from 20 patients. The results are compared to the ones presented by related works to help elucidating the mechanisms of neurotoxicity associated to a decrease in memory, learning and motor skills.

PATIENTS AND

METHODS

Twenty patients with rectal adenocarcinoma were scanned before and after neoadjuvant chemoradiation based exclusively on 5-fluorouracil and leucovorin. The sample was non-rigidly registered to a common template to allow for the comparison of regional metabolism. Statistical analysis was based on adjusted paired t-tests.

RESULTS

The analysis primarily revealed a statistically significant decrease in the metabolism after neoadjuvant chemotherapy at the hypothalamus, putamen, head of the caudate, globus pallidus, red nucleus, substantia nigra, amygdala, cerebellum and the parahippocampal gyrus. The analysis also revealed smaller regions of increased metabolic activity at the middle temporal gyrus, precuneus of the parietal lobe and cuneus of the occipital lobe.

CONCLUSIONS

The regions of decreased metabolism detected in the study are related to memory, learning and voluntary movement which is consistent with previous findings based on clinical studies and neuropsychological tests that report impairments on neurocognitive and motor skills associated to these therapies.