Alterations in brain structure and function after chemotherapy for cancer

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.

Integrating imaging findings in evaluating the post-chemotherapy brain

Cognitive complaints following cancer and cancer therapy are common. Many studies have investigated the effects of chemotherapy on the brain. However, the mechanisms for the associated cognitive impairment are not well understood. Some studies have also included brain imaging to investigate potential neurological substrates of cognitive changes. This review examines recent neuroimaging studies on cancer- and chemotherapy-related cognitive dysfunction in non-central nervous system cancers and compares findings across imaging modalities. Grey matter volume reductions and decreases in white matter integrity are seen after exposure to adjuvant chemotherapy for breast cancer, and functional studies have illuminated both hypo- and hyperactivations in many of the same regions months to years following therapy. These comparisons can assist in further characterizing the dysfunction reported by patients and contribute to a better understanding of the mechanisms involved.