Neurocognitive Effects of Chemotherapy for Colorectal Cancer: A Systematic Review and a Meta-Analysis of 11 Studies

Neurocognitive function and quality-of-life in patients with colorectal cancer

OBJECTIVE

Colorectal cancer (CRC) survivors report significant long-term physical and cognitive declines post-treatment. Our purpose was to combine task-evoked Event-Related Potential (ERP) and resting state functional magnetic resonance imaging (rsf/MRI) methodologies to characterize the physiological underpinnings and cognitive sequelae of chemotherapy-related cognitive impairment, including changes in Quality-Of-Life (QOL) in patients with CRC, as compared to healthy control (HC) participants.

METHODS

This descriptive study recruited and obtained baseline data from patients with CRC at medical and surgical oncology visits four to six weeks post-op and followed them at 12- and 24-weeks. Procedures employed ERP, pencil and paper neuropsychological testing (N-P), structural/functional rsf/MRI, and self-report QOL methodologies. Data analyses included correlations, one-way ANOVA, Chi-square tests, and linear mixed models.

RESULTS

Study participants (n = 40) across groups (n = 15, 11, 14) were balanced on age, sex, education, and race, but not ^{marital status} Several significant associations were found between changes in Dorsal Attention Network (DAN)-related ERP measures (P2, N2, N2P2, N2pc amplitudes), with QOL measures between baseline and last visits (p < 0.05-0.001). Additionally, rsf/MRI findings showed increased network activity in a single node of the DAN post-treatment, which was associated with poorer performance on N-P tests of attention and working memory, as well as a focal decline in grey matter volume in the area.

CONCLUSIONS

Our methodology revealed structural and functional changes within the DAN associated with altered spatial attention, working memory, and ability to inhibit. These disruptions may be responsible for decreased QOL ratings in patients with CRC. This study provides a putative mechanism of understanding how altered brain structural/functional relationships impact cognition, QOL, and nursing care in patients with CRC.

NCI TRIAL ID

NCI-2020-05952, University of Nebraska Medical Center, Clinical Trials.gov ID NCT03683004.

Neurological Complications of Conventional and Novel Anticancer Treatments

Various neurological complications, affecting both the central and peripheral nervous system, can frequently be experienced by cancer survivors after exposure to conventional chemotherapy, but also to modern immunotherapy. In this review, we provide an overview of the most well-known adverse events related to chemotherapy, with a focus on chemotherapy induced peripheral neurotoxicity, but we also address some emerging novel clinical entities related to cancer treatment, including chemotherapy-related cognitive impairment and immune-mediated adverse events. Unfortunately, efficacious curative or preventive treatment for all these neurological complications is still lacking. We provide a description of the possible mechanisms involved to drive future drug discovery in this field, both for symptomatic treatment and neuroprotection.

Chemotherapy-induced functional brain abnormality in colorectal cancer patients: a resting‐state functional magnetic resonance imaging study

Introduction

Chemotherapy-induced cognitive impairment (i.e., “chemobrain”) is a common neurotoxic side-effect experienced by many cancer survivors who undergone chemotherapy. However, the central mechanism underlying chemotherapy-related cognitive impairment is still unclear. The purpose of this study was to investigate the changes of intrinsic brain activity and their associations with cognitive impairment in colorectal cancer (CRC) patients after chemotherapy.

Methods

Resting‐state functional magnetic resonance imaging data of 29 CRC patients following chemotherapy and 29 matched healthy controls (HCs) were collected in this study, as well as cognitive test data including Mini Mental State Exam (MMSE), Montreal Cognitive Assessment (MoCA) and Functional Assessment of Cancer Therapy-Cognitive Function (FACT-Cog). The measure of fractional amplitude of low-frequency fluctuation (fALFF) was calculated and compared between groups. The correlations between the fALFF of impaired brain region and cognitive performance were also analyzed.

Results

Compared with HCs, CRC patients following chemotherapy showed decreased fALFF values in the left anterior cingulate gyrus (ACG) and middle frontal gyrus, as well as increased fALFF values in the left superior frontal gyrus (orbital part) and middle occipital gyrus. Moreover, positive associations were identified between fALFF values of the left ACG and the total scores of MMSE, MoCA and FACT-Cog in the patient group.

Conclusion

These findings indicated that CRC patients after chemotherapy had decreased intrinsic brain activity in the left ACG, which might be vulnerable to the neurotoxic side-effect of chemotherapeutic drugs and related to chemotherapy-induced cognitive impairment.

Long-term neurocognitive function after whole-brain radiotherapy in patients with melanoma brain metastases in the era of immunotherapy

BACKGROUND

Whole-brain radiotherapy (WBRT) used to be standard of care for patients suffering from melanoma brain metastases (MBM) and may still be applicable in selected cases. Deterioration of neurocognitive function (NCF) is commonly seen during and after WBRT. Knowledge on long-term effects in melanoma patients is limited due to short survival rates. With the introduction of immune checkpoint inhibitors, patients may experience ongoing disease control, emphasizing the need for paying more attention to potential long-term adverse effects.

METHODS

In this single-center study, we identified in a period of 11 years all long-term survivors of MBM who received WBRT at least 1 year prior to inclusion. NCF was assessed by Neuropsychological Assessment Battery (NAB) screening and detailed neurological exam; confounders were documented.

RESULTS

Eight patients (median age 55 years) could be identified with a median follow-up of 5.4 years after WBRT. Six patients reported no subjective neurological impairment. NAB screening revealed an average-range score in 5/8 patients. In 3/8 patients a NAB score below average was obtained, correlating with subjective memory deficits in 2 patients. In these patients, limited performance shown in modalities like memory function, attention, and spatial abilities may be considerably attributed to metastasis localization itself. Six out of 8 patients were able to return to their previous work.

CONCLUSION

Five of 8 long-term survivors with MBM after WBRT experienced little to no restriction in everyday activities. In 3 out of 8 patients, cognitive decline was primarily explained by localization of the metastases in functionally relevant areas of the brain. The results of our small patient cohort do not support general avoidance of WBRT for treatment of brain metastases. However, long-term studies including pretreatment NCF tests are needed to fully analyze the long-term neurocognitive effects of WBRT.

Effect of chemotherapy and radiotherapy on cognitive impairment in colorectal cancer: evidence from national representative longitudinal database

Objectives

We aimed to assess the risk of chemotherapy- and radiotherapy-related cognitive impairment in colorectal cancer patients.

Methods

Medical use data of colorectal cancer patients were obtained from Korean National Health Insurance Database (NHID), 2004-2018. We randomly selected 40% of colorectal cancer patients (N=148,848). Cognitive impairment cases were defined as having one or more ICD-10 diagnostic codes for dementia or mild cognitive impairment. Patients aged 18 or younger, patients diagnosed with cognitive impairment before colorectal cancer diagnosis (N=8,225) and those who did not receive primary resection (N=45,320) were excluded. The effects of each chemotherapy regimen on cognitive impairment were estimated. We additionally estimated the effect of radiotherapy in rectal cancer patients. Time-dependent competing risk Cox regression was conducted to estimate overall and age-specific hazard ratios (HR) separately for colon and rectal cancer. Landmark analyses with different lag times were conducted as sensitivity analyses.

Results

Chemotherapy did not increase the risk of cognitive impairment in colorectal cancer (colon cancer: HR=0.92, 95% CI 0.83-1.03; rectal cancer: HR=0.88, 95% CI 0.75-1.04). Radiotherapy was negatively associated with cognitive impairment in rectal cancer (HR=0.01, 95% CI 0.84-0.99). Heterogeneous direction of association by regimen combination was detected. Adverse cognitive effect of certain chemotherapy regimen was more prominent in elderly patients.

Conclusion

Chemotherapy and radiotherapy did not increase the risk of cognitive impairment. Elderly patients with low cognitive reserve could be affected by adverse cognitive effects of chemotherapy. Folate administration showed protective effect against possible cognitive impairment.