Catechol-O-methyltransferase genotype modulates cancer treatment-related cognitive deficits in breast cancer survivors

International Cognition and Cancer Task Force Recommendations for Neuroimaging Methods in the Study of Cognitive Impairment in Non-CNS Cancer Patients

Cancer- and treatment-related cognitive changes have been a focus of increasing research since the early 1980s, with meta-analyses demonstrating poorer performance in cancer patients in cognitive domains including executive functions, processing speed, and memory. To facilitate collaborative efforts, in 2011 the International Cognition and Cancer Task Force (ICCTF) published consensus recommendations for core neuropsychological tests for studies of cancer populations. Over the past decade, studies have used neuroimaging techniques, including structural and functional magnetic resonance imaging (fMRI) and positron emission tomography, to examine the underlying brain basis for cancer- and treatment-related cognitive declines. As yet, however, there have been no consensus recommendations to guide researchers new to this field or to promote the ability to combine data sets. We first discuss important methodological issues with regard to neuroimaging study design, scanner considerations, and sequence selection, focusing on concerns relevant to cancer populations. We propose a minimum recommended set of sequences, including a high-resolution T1-weighted volume and a resting state fMRI scan. Additional advanced imaging sequences are discussed for consideration when feasible, including task-based fMRI and diffusion tensor imaging. Important image data processing and analytic considerations are also reviewed. These recommendations are offered to facilitate increased use of neuroimaging in studies of cancer- and treatment-related cognitive dysfunction. They are not intended to discourage investigator-initiated efforts to develop cutting-edge techniques, which will be helpful in advancing the state of the knowledge. Use of common imaging protocols will facilitate multicenter and data-pooling initiatives, which are needed to address critical mechanistic research questions.

Brain metastases and treatment: multiplying cognitive toxicities

INTRODUCTION

Thirty per cent of cancer patients develop brain metastases, with multiple combination or sequential treatment modalities available, to treat systemic or central nervous system (CNS) disease. Most patients experience toxicities as a result of these treatments, of which cognitive impairment is one of the adverse events most commonly reported, causing major impairment of the patient's quality of life. Areas covered: This article reviews the role of cancer treatments in cognitive decline of patients with brain metastases: surgery, radiotherapy, chemotherapy, targeted therapies, immunotherapies and hormone therapy. Pathological and molecular mechanisms, as well as future directions for limiting cognitive toxicities are also presented. Other causes of cognitive impairment in this population are discussed in order to refine the benefit-risk balance of each treatment modality. Expert opinion: Cumulative cognitive toxicity should be taken into account, and tailored to the patient's cognitive risk in the light of the expected survival benefit. Standardization of cognitive assessment in this context is needed in order to better appreciate each treatment's responsibility in cognitive impairment, keeping in mind disease itself impacts cognition in this context.

Impact of Cognitive Impairment in Patients with Gliomas

OBJECTIVES

To address the estimated rates of incidence, potential underlying etiologies, and cognitive domains affected from diagnosis and treatment. To describe potential cognitive function interventions.

DATA SOURCES

PubMed.

CONCLUSION

Adults with gliomas report that the most distressing, persistent, and greatest negative impact on their lives relates to the cognitive impairment they experience. However, there are several potential interventions that may prevent cognitive decline during treatment or maintain cognitive function long term.

IMPLICATIONS FOR NURSING PRACTICE

Awareness of cognitive sequela that adults with gliomas face can lead to early identification, full neurocognitive profiling, and implementation of evidence-based interventions for those experiencing cognitive impairments following cancer treatment.

Replication and Meta-analysis of the Association between BDNF Val66Met Polymorphism and Cognitive Impairment in Patients Receiving Chemotherapy

Cancer-related cognitive impairment (CRCI) adversely affects cancer patients. We had previously demonstrated that the BDNF Val66Met genetic polymorphism is associated with lower odds of subjective CRCI in the multitasking and verbal ability domains among breast cancer patients receiving chemotherapy. To further assess our previous findings, we evaluated the association of BDNF Val66Met polymorphism with subjective and objective CRCI in a temporally separate cohort of patients and pooled findings from both the original (n = 145) and current (n = 193) cohorts in a meta-analysis. Subjective CRCI was assessed using FACT-Cog. Objective CRCI was evaluated using computerized neuropsychological tests. Genotyping was carried out using Sanger sequencing. The association of BDNF Val66Met genotypes and CRCI was examined with logistic regression. A fixed-effect meta-analysis was conducted using the inverse variance method. In the meta-analysis (n = 338), significantly lower odds of CRCI were associated with Met allele carriers based on the global FACT-Cog score (OR = 0.52, 95% CI 0.29–0.94). Furthermore, Met allele carriers were at lower odds of developing impairment in the domains of memory (OR = 0.34, 95% CI: 0.17–0.70), multitasking (OR = 0.33, 95% CI: 0.18–0.59), and verbal ability (OR = 0.46, 95% CI: 0.24–0.88). Consistent with the previous study, lower odds of subjective CRCI among patients with the BDNF Met allele was observed after adjusting for potential confounders in the multitasking (OR = 0.30, 95% CI: 0.14–0.67) domain. In conclusion, carriers of the BDNF Met allele were protected against global subjective CRCI, particularly in the domains of memory, multitasking, and verbal ability. Our findings further contribute to the understanding of CRCI pathophysiology.

Systematic review of genetic polymorphisms associated with psychoneurological symptoms in breast cancer survivors

PURPOSE

Psychoneurological (PN) symptoms, such as anxiety, cognitive impairment, depression, fatigue, sleep disturbances, and pain, are highly prevalent in breast cancer patients undergoing cancer treatment. Emerging evidence suggests that genetic polymorphisms may contribute to differential symptom susceptibility. We aimed to systematically review associations between genetic polymorphisms and PN symptoms during or after cancer treatment for early-stage breast cancer.

METHODS

Twenty-six eligible articles published until October 2017 were identified in PubMed, PsycINFO, Web of Science, and additional records. Information on study characteristics, genetic polymorphisms, and PN symptoms was extracted. Study quality was evaluated by the STrengthening the REporting of Genetic Association (STREGA) guideline. Genes included in the analysis were categorized by biological pathways based on the Reactome database.

RESULTS

A total of 54 single nucleotide polymorphisms and haplotypes that are significantly associated with PN symptoms were identified; half of them were associated with increased severity of PN symptoms, while the other half contributed to the decrease of PN symptoms. Pain has the known highest number of associated genetic polymorphisms reported, followed by fatigue, cognitive impairment, depressive symptoms, sleep disturbances, and anxiety. The majority of genetic polymorphisms were involved in immune system and neuronal system pathways. Most studies were unsuccessful in meeting the STREGA guideline, which requires transparent reporting of methods and results.

CONCLUSIONS

This review provides comprehensive evidence of genetic polymorphisms underlying PN symptoms, which may pave the way for the development of personalized therapeutics targeting these symptoms. More well-designed genome-wide association studies are required to validate and replicate these findings.

Cancer-Related Cognitive Outcomes Among Older Breast Cancer Survivors in the Thinking and Living With Cancer Study

PURPOSE

To determine treatment and aging-related effects on longitudinal cognitive function in older breast cancer survivors.

METHODS

Newly diagnosed nonmetastatic breast cancer survivors (n = 344) and matched controls without cancer (n = 347) 60 years of age and older without dementia or neurologic disease were recruited between August 2010 and December 2015. Data collection occurred during presystemic treatment/control enrollment and at 12 and 24 months through biospecimens; surveys; self-reported Functional Assessment of Cancer Therapy-Cognitive Function; and neuropsychological tests that measured attention, processing speed, and executive function (APE) and learning and memory (LM). Linear mixed-effects models tested two-way interactions of treatment group (control, chemotherapy with or without hormonal therapy, and hormonal therapy) and time and explored three-way interactions of ApoE (ε4+ v not) by group by time; covariates included baseline age, frailty, race, and cognitive reserve.

RESULTS

Survivors and controls were 60 to 98 years of age, were well educated, and had similar baseline cognitive scores. Treatment was related to longitudinal cognition scores, with survivors who received chemotherapy having increasingly worse APE scores ( P = .05) and those initiating hormonal therapy having lower LM scores at 12 months ( P = .03) than other groups. These group-by-time differences varied by ApoE genotype, where only ε4+ survivors receiving hormone therapy had short-term decreases in adjusted LM scores (three-way interaction P = .03). For APE, the three-way interaction was not significant ( P = .14), but scores were significantly lower for ε4+ survivors exposed to chemotherapy (-0.40; 95% CI, -0.79 to -0.01) at 24 months than ε4+ controls (0.01; 95% CI, 0.16 to 0.18; P < .05). Increasing age was associated with lower baseline scores on all cognitive measures ( P < .001); frailty was associated with baseline APE and self-reported decline ( P < .001).

CONCLUSION

Breast cancer systemic treatment and aging-related phenotypes and genotypes are associated with longitudinal decreases in cognitive function scores in older survivors. These data could inform treatment decision making and survivorship care planning.

Cognitive Changes in Cancer Survivors

Advances in cancer treatments have led to substantially improved survival for patients with cancer. However, many patients experience changes in cognition as a side effect of both cancer and cancer treatment. This occurs with both central nervous system (CNS) tumors and non-CNS tumors and in both children and adults. Studies of patients with non-CNS cancer have shown that cancer-related cognitive impairment (CRCI), which can include changes in memory, executive function, attention, and processing speed, occurs in up to 30% of patients prior to any treatment and in up to 75% of patients during treatment. A subset of patients with non-CNS and CNS cancer appear to be at higher risk for CRCI, so much research has gone into identifying who is vulnerable. Risk factors for CRCI in adults include cognitive reserve, age, genetic factors, and ethnicity; risk factors for children include genetic factors, female sex, younger age at diagnosis, chemotherapy dose, and both dose and field size for radiation. Although the field has made substantial strides in understanding and treating CRCI, more research is still needed to improve outcomes for both pediatric and adult cancer survivors.

Cognitive Effects of Cancer and Cancer Treatments

As the population of cancer survivors has grown into the millions, there has been increasing emphasis on understanding how the late effects of treatment affect survivors' ability to return to work/school, their capacity to function and live independently, and their overall quality of life. This review focuses on cognitive change associated with cancer and cancer treatments. Research in this area has progressed from a pharmacotoxicology perspective to a view of the cognitive change as a complex interaction of aspects of the treatment, vulnerability factors that increase risk for posttreatment cognitive decline, cancer biology, and the biology of aging. Methodological advances include the development of (a) measurement approaches that assess more fine-grained subcomponents of cognition based on cognitive neuroscience and (b) advanced statistical approaches. Conceptual issues that arise from this multidimensional perspective are described in relation to future directions, understanding of mechanisms, and development of innovative interventions.

Cognitive Effects of Chemotherapy and Cancer-Related Treatments in Older Adults

Advances in cancer treatment are producing a growing number of cancer survivors; therefore, issues surrounding quality of life during and following cancer treatment have become increasingly important. Chemotherapy-related cognitive impairment (CRCI) is a problem that is commonly reported following the administration of chemotherapy treatment in patients with cancer. Research suggests that CRCI can persist for months to years after completing treatment, which has implications for the trajectory of normal and pathologic cognitive aging for the growing number of long-term cancer survivors. These problems are particularly relevant for older individuals, given that cancer is largely a disease of older age, and the number of patients with cancer who are aged 65 years or older will increase dramatically over the coming decades. This review will briefly summarize empirical findings related to CRCI, discuss CRCI in older patients with cancer, propose potential causative hypotheses, and provide a canonical patient case to illustrate how CRCI presents clinically. Finally, potential intervention strategies for CRCI will be highlighted and issues to consider when evaluating older patients with a history of cancer will be discussed.

Cognitive Changes Related to Cancer Therapy

A growing population of cancer survivors is at risk for acute and long-term consequences resulting from cancer and its treatment. Cancer-related cognitive impairment (CRCI) typically manifests as modest deficits in attention, processing speed, executive functioning, and memory, which may persist for decades after treatment. Although some risk factors for CRCI are largely immutable (eg, genetics and demographic factors), there are many other contributors to CRCI that when appropriately addressed can result in improved cognitive functioning and quality of life. Neuropsychological assessment can help identify patient cognitive strengths and weaknesses, target psychological and behavioral contributors to CRCI, and guide treatment interventions.

Mechanisms of Neurotoxic Symptoms as a Result of Breast Cancer and Its Treatment: Considerations on the Contribution of Stress, Inflammation, and Cellular Bioenergetics

PURPOSE OF REVIEW

Breast cancer and its treatment are associated with a range of neurotoxic symptoms, such as fatigue, cognitive impairment, and pain. Although these symptoms generally subside after treatment completion, they become chronic in a significant subset of patients. We here summarize recent findings on neuroinflammation, stress, and mitochondrial dysfunction as mechanistic pathways leading to neurotoxic symptom experience in breast cancer patients and survivors.

RECENT FINDINGS

Neuroinflammation related to stress or cancer treatment and stress resulting from diagnosis, treatment, or (cancer-related) worrying are important predictors of a neurotoxic symptom experience, both during and after treatment for breast cancer. Both inflammation and stress hormones, as well as cancer treatment, can induce mitochondrial dysfunction resulting in reduced cellular energy.

SUMMARY

We propose reduced cellular energy (mitochondrial dysfunction) induced by inflammation, oxygen radical production, and stress as a result of cancer and/or cancer treatment as a final mechanism underlying neurotoxic symptoms.

A systemic literature review of neuroimaging studies in women with breast cancer treated with adjuvant chemotherapy

Chemotherapy-induced cognitive deficits in patients with breast cancer, predominantly in attention and verbal memory, have been observed in numerous studies. These neuropsychological findings are corroborated by the results of neuroimaging studies. The aim of this paper was to survey the reports on cerebral structural and functional alterations in women with breast cancer treated with chemotherapy (CTx). First, we discuss the host-related and disease-related mechanisms underlying cognitive impairment after CTx. We point out the direct and indirect neurotoxic effect of cytostatics, which may cause: a damage to neurons or glial cells, changes in neurotransmitter levels, deregulation of the immune system and/or cytokine release. Second, we focus on the results of neuroimaging studies on brain structure and function that revealed decreased: density of grey matter, integrity of white matter and volume of multiple brain regions, as well as their lower activation during cognitive task performance. Finally, we concentrate on compensatory mechanisms, which activate additional brain areas or neural connection to reach the premorbid cognitive efficiency.

Biomarkers Associated with Cognitive Impairment in Treated Cancer Patients: Potential Predisposition and Risk Factors

Purpose: Cognitive impairment in cancer patients induced, at least in part, by treatment are frequently observed and likely have negative impacts on patient quality of life. Such cognitive dysfunctions can affect attention, executive functions, and memory and processing speed, can persist after treatment, and their exact causes remain unclear. The aim of this review was to create an inventory and analysis of clinical studies evaluating biological markers and risk factors for cognitive decline in cancer patients before, during, or after therapy. The ultimate objectives were to identify robust markers and to determine what further research is required to develop original biological markers to enable prevention or adapted treatment management of patients at risk.

Method: This review was guided by the PRISMA statement and included a search strategy focused on three components: “cognition disorders,” “predictive factors”/“biological markers,” and “neoplasms,” searched in PubMed since 2005, with exclusion criteria concerning brain tumors, brain therapy, and imaging or animal studies.

Results: Twenty-three studies meeting the criteria were analyzed. Potential associations/correlations were identified between cognitive impairments and specific circulating factors, cerebral spinal fluid constituents, and genetic polymorphisms at baseline, during, and at the end of treatment in cancer populations. The most significant results were associations between cognitive dysfunctions and genetic polymorphisms, including APOE-4 and COMT-Val; increased plasma levels of the pro-inflammatory cytokine, IL-6; anemia; and hemoglobin levels during chemotherapy. Plasma levels of specific hormones of the hypothalamo-pituitary-adrenal axis are also modified by treatment.

Discussion: It is recognized in the field of cancer cognition that cancer and comorbidities, as well as chemotherapy and hormone therapy, can cause persistent cognitive dysfunction. A number of biological circulating factors and genetic polymorphisms, can predispose to the development of cognitive disorders. However, many predictive factors remain unproven and discordant findings are frequently reported, warranting additional clinical and preclinical longitudinal cohort studies, with goals of better characterization of potential biomarkers and identification of patient populations at risk and/or particularly deleterious treatments. Research should focus on prevention and personalized cancer management, to improve the daily lives, autonomy, and return to work of patients.

An exploratory study of host polymorphisms in genes that clinically characterize breast cancer tumors and pretreatment cognitive performance in breast cancer survivors

PURPOSE

Inspired by the hypothesis that heterogeneity in the biology of breast cancers at the cellular level may account for cognitive dysfunction symptom variability in survivors, the current study explored relationships between host single-nucleotide polymorphisms (SNPs) in 25 breast cancer-related candidate genes (AURKA, BAG1, BCL2, BIRC5, CCNB1, CD68, CENPA, CMC2, CTSL2, DIAPH3, ERBB2, ESR1, GRB7, GSTM1, MELK, MKI67, MMP11, MYBL2, NDC80, ORC6, PGR, RACGAP1, RFC4, RRM2, and SCUBE2), identified from clinically relevant prognostic multigene-expression profiles for breast cancer, and pretreatment cognitive performance.

PATIENTS AND METHODS

The sample (n=220) was comprised of 138 postmenopausal women newly diagnosed with early stage breast cancer and 82 postmenopausal age- and education-matched healthy controls without breast cancer. Cognitive performance was assessed after primary surgery but prior to initiation of adjuvant chemotherapy and/or hormonal therapy using a comprehensive battery of neuropsychological tests encompassing eight cognitive function composite domains: attention, concentration, executive function, mental flexibility, psychomotor speed, verbal memory, visual memory, and visual working memory. In total, 131 SNPs were included in the analysis. Standard and robust multiple linear regression modeling was used to examine relationships between each domain and the presence or absence of one or more minor alleles for each SNP. Genetic risk/protection scores (GRSs) were calculated for each domain to evaluate the collective effect of possession of multiple risk/protective alleles.

RESULTS

With the exception of CMC2, MMP11, and RACGAP1, significant (P<0.05) SNP main effect and/or SNP by future prescribed treatment group interactions were observed for every gene between at least one domain and one or more SNPs. All GRSs were found to be significantly (P<0.001) associated with each respective domain score.

CONCLUSION

Associations between host SNPs and computed GRSs and variability in pretreatment cognitive function performance support the study hypothesis, and warrant further investigations to identify biomarkers for breast cancer-related cognitive dysfunction.

Cognitive impairment following hormone therapy: current opinion of research in breast and prostate cancer patients

PURPOSE OF REVIEW

Hormone therapy is a common cancer treatment that may be associated with numerous side and late effects, and in recent years, has been linked to changes in cognition. Here, we present the most important recent findings from empirical studies and reviews that have focused on the effects of hormone therapy on cognitive functioning in breast and prostate cancer populations, underline some general shortcomings, and propose directions for future research.

RECENT FINDINGS

Recent research indicates that cognitive impairment may occur in breast and prostate cancer patients following onset of hormone therapy. However, because of methodological shortcomings and heterogeneity of current research, conclusions regarding the effects of hormone therapy on cognitive functions remain tentative.

SUMMARY

The review highlights the general findings while also describing the many methodological shortcomings that need to be addressed in future research. It is clear that larger scale neuropsychological studies that also evaluate the impact of impairments on daily life functioning will improve our understanding of the effects of hormone therapy on cognition and inform the development of appropriate interventions.

COMT, BDNF, and DTNBP1 polymorphisms and cognitive functions in patients with brain tumors

BACKGROUND

Cognitive dysfunction is common among patients with brain tumors and can be associated with the disease and treatment with radiotherapy and chemotherapy. However, little is known about genetic risk factors that may moderate the vulnerability for developing cognitive dysfunction. In this study, we examined the association of single nucleotide polymorphisms (SNPs) in the catechol-O-methyl transferase (COMT), brain-derived neurotrophic factor (BDNF), and dystrobrevin-binding protein 1 (DTNBP1) genes with cognitive functions and neuroimaging outcomes in patients with brain tumors.

METHODS

One hundred and fifty patients with brain tumors completed neuropsychological tests of attention, executive functions, and memory and were genotyped for polymorphisms in the COMT, BDNF, and DTNBP1 genes. Ratings of white matter (WM) abnormalities on magnetic resonance imaging scans were performed.

RESULTS

Multivariate regression shrinkage analyses, adjusted for age, education, treatment type, time since treatment completion, and tumor location, indicated a significant association between the COMT SNP rs4680 (Val158Met) and memory with lower scores in delayed recall (P < .01) among homozygotes (valine/valine). Additional COMT, BDNF and DTNBP1 SNPs were significantly associated with attention, executive functions, and memory scores.

CONCLUSION

This is the first study to suggest that known and newly described polymorphisms in genes associated with executive and memory functions in healthy individuals and other clinical populations may modulate cognitive outcome in patients with brain tumors.

Use of complementary therapies for side effect management in breast cancer: evidence and rationale

Women diagnosed with breast cancer can experience chronic side effects after curative treatment concludes, negatively impacting survivorship. The most prevalent side effects addressed in the medical and nursing literature include symptoms such as hot flashes, fatigue, myalgias/arthralgias and cognitive impairment. Complementary therapies, particularly natural products including herbs, dietary supplements, vitamins, minerals, and probiotics, and mind–body techniques that include such modalities as yoga, meditation, massage, acupuncture, relaxation, tai chi and hypnosis show promise for treatment of some of these symptoms associated with cancer care. However, the research in this area is nascent and much more work is needed to understand symptom physiology and mechanisms of action of complementary therapies. The purpose of this paper was to summarize key evidence from Phase II and III randomized clinical trials in order to provide guidance to distinguish promising versus nonpromising interventions for symptom management.

Chemotherapy-related cognitive impairment in older patients with cancer

Chemotherapy-related cognitive impairment (CRCI) can occur during or after chemotherapy and represents a concern for many patients with cancer. Among older patients with cancer, in whom there is little clinical trial evidence examining side effects like CRCI, many unanswered questions remain regarding risk for and resulting adverse outcomes from CRCI. Given the rising incidence of cancer with age, CRCI is of particular concern for older patients with cancer who receive treatment. Therefore, research related to CRCI in older patients with cancers is a high priority. In this manuscript, we discuss current gaps in research highlighting the lack of clinical studies of CRCI in older adults, the complex mechanisms of CRCI, and the challenges in measuring cognitive impairment in older patients with cancer. Although we focus on CRCI, we also discuss cognitive impairment related to cancer itself and other treatment modalities. We highlight several research priorities to improve the study of CRCI in older patients with cancer.

A clinically relevant dose of cyclophosphamide chemotherapy impairs memory performance on the delayed spatial alternation task that is sustained over time as mice age

BACKGROUND

Cyclophosphamide chemotherapy is a mainstay of adjuvant breast cancer treatment. Unfortunately, this drug is associated with cognitive impairments in cancer patients that may accelerate cognitive aging. Memory is particularly affected in many patients. In order to better understand the precise cognitive impairments caused by this chemotherapy agent, we investigated a clinically relevant dose and administration paradigm on delayed spatial memory abilities in C57BL/6 mice. We utilized a delayed alternation paradigm similar to a delayed match to sample paradigm reported to be sensitive in human neurotoxicology research.

METHODS

A dose of 200mg/kg cyclophosphamide was administered intravenously (at weekly intervals) for 4 weeks to C57BL/6 mice starting at 6 ½ months of age. Memory was tested in mice using a reward-based delayed spatial alternation paradigm with delay values of 1.5, 3, 6.1, 12.4 and 25s presented randomly over 80 sessions (16 reinforcers per session), and testing began at the initiation of chemotherapy through 3 months.

RESULTS

At the longest delay, i.e., that requiring the greatest memory, mice treated with chemotherapy exhibited a significant decline over time in percent correct which leveled off compared to controls that continued to improve slightly.

CONCLUSIONS

Our clinically relevant model shows cyclophosphamide chemotherapy causes a slight decline in delayed spatial memories at the longest delay that is sustained over time as mice age.

Neurocognitive functioning and genetic variation in patients with primary brain tumours

Impairment of neurocognitive functioning is a common result of cerebral neoplasms and treatment, although there is substantial heterogeneity in the pattern and severity of neurocognitive dysfunction across individuals and tumour types. The effects of many clinical and patient characteristics on neurocognitive functioning have been documented, but little research has been devoted to understanding the effect of genetic variation on neurocognitive outcomes in patients with brain tumours. This Review highlights preliminary evidence that suggests an association between various genes and risk of adverse neurocognitive outcomes in patients with brain tumours. Studies include genes specific to neuronal function, and those associated with more systemic cellular regulation. Related scientific literature in other disease populations is briefly discussed to indicate additional candidate genes. We consider methodological issues central to the study of neurocognitive functioning and genetic associations for patients with brain tumours, and emphasise the need for future research integrating novel investigative techniques.

American Cancer Society/American Society of Clinical Oncology Breast Cancer Survivorship Care Guideline

The purpose of the American Cancer Society/American Society of Clinical Oncology Breast Cancer Survivorship Care Guideline is to provide recommendations to assist primary care and other clinicians in the care of female adult survivors of breast cancer. A systematic review of the literature was conducted using PubMed through April 2015. A multidisciplinary expert workgroup with expertise in primary care, gynecology, surgical oncology, medical oncology, radiation oncology, and nursing was formed and tasked with drafting the Breast Cancer Survivorship Care Guideline. A total of 1,073 articles met inclusion criteria; and, after full text review, 237 were included as the evidence base. Patients should undergo regular surveillance for breast cancer recurrence, including evaluation with a cancer-related history and physical examination, and should be screened for new primary breast cancer. Data do not support performing routine laboratory tests or imaging tests in asymptomatic patients to evaluate for breast cancer recurrence. Primary care clinicians should counsel patients about the importance of maintaining a healthy lifestyle, monitor for post-treatment symptoms that can adversely affect quality of life, and monitor for adherence to endocrine therapy. Recommendations provided in this guideline are based on current evidence in the literature and expert consensus opinion. Most of the evidence is not sufficient to warrant a strong evidence-based recommendation. Recommendations on surveillance for breast cancer recurrence, screening for second primary cancers, assessment and management of physical and psychosocial long-term and late effects of breast cancer and its treatment, health promotion, and care coordination/practice implications are made.

This guideline was developed through a collaboration between the American Cancer Society and the American Society of Clinical Oncology and has been published jointly by invitation and consent in both CA: A Cancer Journal for Clinicians and Journal of Clinical Oncology. Copyright © 2015 American Cancer Society and American Society of Clinical Oncology. All rights reserved. No part of this document may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopy, recording, or any information storage and retrieval system, without written permission by the American Cancer Society or the American Society of Clinical Oncology.

American Cancer Society/American Society of Clinical Oncology Breast Cancer Survivorship Care Guideline

Answer questions and earn CME/CNE The purpose of the American Cancer Society/American Society of Clinical Oncology Breast Cancer Survivorship Care Guideline is to provide recommendations to assist primary care and other clinicians in the care of female adult survivors of breast cancer. A systematic review of the literature was conducted using PubMed through April 2015. A multidisciplinary expert workgroup with expertise in primary care, gynecology, surgical oncology, medical oncology, radiation oncology, and nursing was formed and tasked with drafting the Breast Cancer Survivorship Care Guideline. A total of 1073 articles met inclusion criteria; and, after full text review, 237 were included as the evidence base. Patients should undergo regular surveillance for breast cancer recurrence, including evaluation with a cancer-related history and physical examination, and should be screened for new primary breast cancer. Data do not support performing routine laboratory tests or imaging tests in asymptomatic patients to evaluate for breast cancer recurrence. Primary care clinicians should counsel patients about the importance of maintaining a healthy lifestyle, monitor for post-treatment symptoms that can adversely affect quality of life, and monitor for adherence to endocrine therapy. Recommendations provided in this guideline are based on current evidence in the literature and expert consensus opinion. Most of the evidence is not sufficient to warrant a strong evidence-based recommendation. Recommendations on surveillance for breast cancer recurrence, screening for second primary cancers, assessment and management of physical and psychosocial long-term and late effects of breast cancer and its treatment, health promotion, and care coordination/practice implications are made.

Early and late long-term effects of adjuvant chemotherapy

Adjuvant chemotherapy continues to play an important role in breast cancer management. Exposure to chemotherapy can lead to a variety of early and late long-term toxicities, including ovarian failure (with resultant infertility and sexual dysfunction), bone loss, weight gain, neurotoxicity, neurocognitive changes, cardiac toxicity and secondary malignancy. Although chemotherapy effects may vary in medical severity, all effects have the potential to lead to a decrease in quality of life and a decrement on overall health status. Improved understanding of the etiology and management of chemotherapy-related toxicity may allow optimization of patient selection for treatment and ameliorate the concerns of patients who are considering embarking on a chemotherapy program. This article presents an overview of relevant early and late long-term toxicities, with a focus on recent advances and clinical management.

Brain-derived neurotrophic factor genetic polymorphism (rs6265) is protective against chemotherapy-associated cognitive impairment in patients with early-stage breast cancer

Background

Brain-derived neurotrophic factor (BDNF), a neurotrophin that regulates neuronal function and development, is implicated in several neurodegenerative conditions. Preliminary data suggest that a reduction of BDNF concentrations may lead to postchemotherapy cognitive impairment. We hypothesized that a single nucleotide polymorphism (rs6265) of the BDNF gene may predispose patients to cognitive impairment. This study aimed to evaluate the effect of BDNF gene polymorphism on chemotherapy-associated cognitive impairment.

Methods

Overall, 145 patients receiving chemotherapy for early-stage breast cancer (mean age: 50.8 ± 8.8 y; 82.1% Chinese) were recruited. Patients' cognitive functions were assessed longitudinally using the validated Functional Assessment of Cancer Therapy–Cognitive Function (v.3) and an objective computerized tool, Headminder. Genotyping was performed using Sanger sequencing. Logistic regression was used to evaluate the association between BDNF Val66Met polymorphism and cognition after adjusting for ethnicity and clinically important covariates.

Results

Of the 145 patients, 54 (37%) reported cognitive impairment postchemotherapy. The Met/Met genotype was associated with statistically significant lower odds of developing cognitive impairment (odds ratio [OR] = 0.26; 95% CI: 0.08–0.92; P = .036). The Met carriers were less likely to experience impairment in the domains of verbal fluency (OR = 0.34; 95% CI: 0.12–0.90; P = .031) and multitasking ability (OR = 0.37; 95% CI: 0.15–0.91; P = .030) compared with the Val/Val homozygote. No associations were observed between Headminder and the BDNF Val66Met polymorphism.

Conclusions

This is the first study to provide evidence that carriers of the BDNF Met allele are protected against chemotherapy-associated cognitive impairment. Further studies are required to validate the findings.

Apolipoprotein E genotype and cognitive function in postmenopausal women with early-stage breast cancer

PURPOSE/OBJECTIVES

To examine the role of apolipoprotein E (APOE) genotype in the cognitive function of postmenopausal women with early-stage breast cancer prior to initiation of adjuvant therapy and over time with treatment.

DESIGN

Longitudinal, genetic association study.

SETTING

Urban university cancer center.

SAMPLE

Three cohorts of postmenopausal women: 37 women with breast cancer receiving chemotherapy and anastrozole, 41 women with breast cancer receiving anastrozole alone, and 50 healthy women.

METHODS

Cognitive function was evaluated three times during a 12-month period using a comprehensive neuropsychological test battery. Participants were genotyped and classified based on the presence or absence of at least one APOE e4 allele. Multiple linear regression was used to determine if APOE genotype accounted for observed variability in cognitive function data.

MAIN RESEARCH VARIABLES

APOE genotype, breast cancer treatment, and cognitive function.

FINDINGS

Performance or changes in performance on tasks of executive function, attention, verbal learning and memory, and visual learning and memory were found to be influenced by APOE genotype and/or interactions between APOE genotype and study cohort.

CONCLUSIONS

The results indicate that cognitive function in postmenopausal women with breast cancer is modified by APOE genotype and the combination of APOE genotype and treatment.

IMPLICATIONS FOR NURSING

APOE genotype, along with other biomarkers, may be used in the future to assist nurses in identifying women with breast cancer most at risk for cognitive decline.

Course and Predictors of Cognitive Function in Patients With Prostate Cancer Receiving Androgen-Deprivation Therapy: A Controlled Comparison

PURPOSE

Men receiving androgen-deprivation therapy (ADT) for prostate cancer may be at risk for cognitive impairment; however, evidence is mixed in the existing literature. Our study examined the impact of ADT on impaired cognitive performance and explored potential demographic and genetic predictors of impaired performance.

PATIENTS AND METHODS

Patients with prostate cancer were assessed before or within 21 days of starting ADT (n = 58) and 6 and 12 months later. Age- and education-matched patients with prostate cancer treated with prostatectomy only (n = 84) and men without prostate cancer (n = 88) were assessed at similar intervals. Participants provided baseline blood samples for genotyping. Mean-level cognitive performance was compared using mixed models; cognitive impairment was compared using generalized estimating equations.

RESULTS

ADT recipients demonstrated higher rates of impaired cognitive performance over time relative to all controls (P = .01). Groups did not differ at baseline (P > .05); however, ADT recipients were more likely to demonstrate impaired performance within 6 and 12 months (P for both comparisons < .05). Baseline age, cognitive reserve, depressive symptoms, fatigue, and hot flash interference did not moderate the impact of ADT on impaired cognitive performance (P for all comparisons ≥ .09). In exploratory genetic analyses, GNB3 single-nucleotide polymorphism rs1047776 was associated with increased rates of impaired performance over time in the ADT group (P < .001).

CONCLUSION

Men treated with ADT were more likely to demonstrate impaired cognitive performance within 6 months after starting ADT relative to matched controls and to continue to do so within 12 months after starting ADT. If confirmed, findings may have implications for patient education regarding the risks and benefits of ADT.

Brain network alterations and vulnerability to simulated neurodegeneration in breast cancer

Breast cancer and its treatments are associated with mild cognitive impairment and brain changes that could indicate an altered or accelerated brain aging process. We applied diffusion tensor imaging and graph theory to measure white matter organization and connectivity in 34 breast cancer survivors compared with 36 matched healthy female controls. We also investigated how brain networks (connectomes) in each group responded to simulated neurodegeneration based on network attack analysis. Compared with controls, the breast cancer group demonstrated significantly lower fractional anisotropy, altered small-world connectome properties, lower brain network tolerance to systematic region (node), and connection (edge) attacks and significant cognitive impairment. Lower tolerance to network attack was associated with cognitive impairment in the breast cancer group. These findings provide further evidence of diffuse white matter pathology after breast cancer and extend the literature in this area with unique data demonstrating increased vulnerability of the post-breast cancer brain network to future neurodegenerative processes.

Moderating Effects of Genetic Polymorphisms on Improvements in Cognitive Impairment in Breast Cancer Survivors Participating in a 6-Week Mindfulness-Based Stress Reduction Program

Breast cancer (BC) survivors often report cognitive impairment, which may be influenced by single-nucleotide polymorphisms (SNPs). The purpose of this study was to test whether particular SNPs were associated with changes in cognitive function in BC survivors and whether these polymorphisms moderated cognitive improvement resulting from the Mindfulness-Based Stress Reduction for Breast Cancer (MBSR[BC]) program. BC survivors recruited from Moffitt Cancer Center and the University of South Florida's Breast Health Program, who had completed adjuvant radiation and/or chemotherapy treatment, were randomized to either the 6-week MBSR(BC) program (n = 37) or usual care (UC; n = 35) group. Measures of cognitive function and demographic and clinical history data were attained at baseline and at 6 and 12 weeks. A total of 10 SNPs from eight genes known to be related to cognitive function were analyzed using blood samples. Results showed that SNPs in four genes (ankyrin repeat and kinase domain containing 1 [ANKK1], apolipoprotein E [APOE], methylenetetrahydrofolate reductase [MTHFR], and solute carrier family 6 member 4 [SLC6A4]) were associated with cognitive impairment. Further, rs1800497 in ANKK1 was significantly associated with improvements in cognitive impairment in response to MBSR(BC). These results may help to identify individuals who would be better served by MBSR(BC) or other interventions.

Associations between catecholaminergic, GABAergic, and serotonergic genes and self-reported attentional function in oncology patients and their family caregivers

PURPOSE OF THE RESEARCH

Evaluate for associations between variations in genes involved in catecholaminergic, gamma-aminobutyric acid (GABA)-ergic, and serotonergic mechanisms of neurotransmission and attentional function latent classes.

PATIENTS AND METHODS

This descriptive, longitudinal study was conducted at two radiation therapy departments. The sample included three latent classes of individuals with distinct trajectories of self-reported attentional function during radiation therapy, who were previously identified using growth mixture modeling among 167 oncology patients and 85 of their family caregivers. Multivariable models were used to evaluate for genotypic associations of neurotransmission genes with attentional function latent class membership, after controlling for covariates.

RESULTS

Variations in catecholaminergic (i.e., ADRA1D rs4815675, SLC6A3 rs37022), GABAergic (i.e., SLC6A1 rs2697138), and serotonergic (i.e., HTR2A rs2296972, rs9534496) neurotransmission genes were significant predictors of latent class membership in multivariable models.

CONCLUSIONS

Findings suggest that variations in genes that encode for three distinct but related neurotransmission systems are involved in alterations in attentional function. Knowledge of both phenotypic and genetic markers associated with alterations in attentional function can be used by clinicians to identify patients and family caregivers who are at higher risk for this symptom. Increased understanding of the genetic markers associated with alterations in attentional function may provide insights into the underlying mechanisms for this significant clinical problem.

The genetic variants underlying breast cancer treatment-induced chronic and late toxicities: a systematic review

A systematic review was performed to describe the findings from 19 genetic association studies that have examined the genetic variants underlying four common treatment-induced chronic and late toxicities in breast cancer patients, and to evaluate the quality of reporting. Three out of 5 studies found an association between HER2 lle655Val polymorphisms and trastuzumab-induced cardiotoxicity. Two studies found a positive association between cognitive impairment and the Val allele of the COMT gene and the ε4 allele of the apolipoprotein E gene. Genetic associations were established between fatigue and the G/G genotype of IL6-174 and TNF-308, and the Met allele of the COMT gene in 4 studies. Among studies (N=8) that evaluated the genetic associations underlying peripheral neuropathy, CYP2C8∗3 variant is commonly reported as the associated gene. Most studies failed to conform to the major criteria listed in the STREGA guidelines, with a lack of transparent reporting of methods and results.

Brain development, experience, and behavior

Brain development progresses through a series of stages beginning with neurogenesis and progressing to neural migration, maturation, synaptogenesis, pruning, and myelin formation. This review examines the literature on how early experiences alter brain development, including environmental events such as sensory stimuli, early stress, psychoactive drugs, parent-child relationships, peer relationships, intestinal flora, diet, and radiation. This sensitivity of the brain to early experiences has important implications for understanding neurodevelopmental disorders as well as the effect of medical interventions in children.

Cognitive effects of cancer systemic therapy: implications for the care of older patients and survivors

The number of patients with cancer who are age 65 years or older (hereinafter "older") is increasing dramatically. One obvious aspect of cancer care for this group is that they are experiencing age-related changes in multiple organ systems, including the brain, which complicates decisions about systemic therapy and assessments of survivorship outcomes. There is a consistent body of evidence from studies that use neuropsychological testing and neuroimaging that supports the existence of impairment following systemic therapy in selected cognitive domains among some older patients with cancer. Impairment in one or more cognitive domains could have important effects in the daily lives of older patients. However, an imperfect understanding of the precise biologic mechanisms underlying cognitive impairment after systemic treatment precludes development of validated methods for predicting which older patients are at risk. From what is known, risks may include lifestyle factors such as smoking, genetic predisposition, and specific comorbidities such as diabetes and cardiovascular disease. Risk also interacts with physiologic and cognitive reserve, because even at the same chronological age and with the same number of illnesses, older patients vary from having high reserve (ie, biologically younger than their age) to being frail (biologically older than their age). Surveillance for the presence of cognitive impairment is also an important component of long-term survivorship care with older patients. Increasing the workforce of cancer care providers who have geriatrics training or who are working within multidisciplinary teams that have this type of expertise would be one avenue toward integrating assessment of the cognitive effects of cancer systemic therapy into routine clinical practice.

A prospective evaluation of changes in brain structure and cognitive functions in adult stem cell transplant recipients

Hematopoietic stem cell transplantation (HSCT) is an efficacious treatment for many hematologic malignancies. However, the conditioning regimen of high-dose (HD) chemotherapy with or without total body irradiation (TBI) can be associated with neurotoxicity. In this prospective study, we used quantitative neuroimaging techniques to examine regional gray matter and ventricular volumes, and standardized neuropsychological tests to assess cognitive function before and 1 year after HSCT in 28 patients with hematologic malignancies and in ten healthy controls evaluated at similar intervals. Nineteen patients received conditioning treatment with HD chemotherapy alone and nine had both TBI and HD chemotherapy. There was a significant reduction in gray matter volume in the middle frontal gyrus bilaterally and in the left caudate nucleus in the patient group (all patients combined) but not among healthy controls over the 1-year follow-up period. There was a significant increase in left lateral ventricle volume and in total ventricle volume in the patient group, relative to healthy controls. Similar brain structural changes were seen for patients treated with HD chemotherapy alone. The neuropsychological results showed that 21% of patients could be classified as impaired at baseline. The Reliable Change Index suggested no significantly different rates of cognitive decline between patients and healthy controls. The findings suggest that HSCT patients may be at an increased risk for developing regional brain volume loss, and that subgroups may experience cognitive dysfunction prior to and 1 year following the transplant.

Interactive effects of KIBRA and CLSTN2 polymorphisms on episodic memory in old-age unipolar depression

The KIBRA (rs17070145) C-allele and the CLSTN2 (rs6439886) T-allele have both been associated with poorer episodic memory performance. Given that episodic memory is affected in depression, we hypothesized that the combination of these risk alleles would be particularly detrimental to episodic memory performance in depressed persons. In the population-based SNAC-K study, 2170 participants (≥ 60 years) without dementia (DSM-IV criteria) and antidepressant pharmacotherapy were clinically examined and diagnosed following ICD-10 criteria for unipolar depression, and genotyped for KIBRA and CLSTN2. Participants were categorized according to unipolar depression status (yes, no) and genotype combinations (KIBRA: CC, any T; CLSTN2: TT, any C). Critically, a three-way interaction effect showed that the CC/TT genotype combination was associated with poorer episodic recall and recognition performance only in depressed elderly persons, with depressed CC/TT carriers consistently performing at the lowest level. This finding supports the view that effects of genetic polymorphisms on cognitive functioning may be most easily disclosed at suboptimal levels of cognitive ability, such as in old-age depression.

Cognitive impairment in older patients with breast cancer before systemic therapy: is there an interaction between cancer and comorbidity?

PURPOSE

To determine if older patients with breast cancer have cognitive impairment before systemic therapy.

PATIENTS AND METHODS

Participants were patients with newly diagnosed nonmetastatic breast cancer and matched friend or community controls age > 60 years without prior systemic treatment, dementia, or neurologic disease. Participants completed surveys and a 55-minute battery of 17 neuropsychological tests. Biospecimens were obtained for APOE genotyping, and clinical data were abstracted. Neuropsychological test scores were standardized using control means and standard deviations (SDs) and grouped into five domain z scores. Cognitive impairment was defined as any domain z score two SDs below or ≥ two z scores 1.5 SDs below the control mean. Multivariable analyses evaluated pretreatment differences considering age, race, education, and site; comparisons between patient cases also controlled for surgery.

RESULTS

The 164 patient cases and 182 controls had similar neuropsychological domain scores. However, among patient cases, those with stage II to III cancers had lower executive function compared with those with stage 0 to I disease, after adjustment (P = .05). The odds of impairment were significantly higher among older, nonwhite, less educated women and those with greater comorbidity, after adjustment. Patient case or control status, anxiety, depression, fatigue, and surgery were not associated with impairment. However, there was an interaction between comorbidity and patient case or control status; comorbidity was strongly associated with impairment among patient cases (adjusted odds ratio, 8.77; 95% CI, 2.06 to 37.4; P = .003) but not among controls (P = .97). Only diabetes and cardiovascular disease were associated with impairment among patient cases.

CONCLUSION

There were no overall differences between patients with breast cancer and controls before systemic treatment, but there may be pretreatment cognitive impairment within subgroups of patient cases with greater tumor or comorbidity burden.

Proposed mechanisms for cancer- and treatment-related cognitive changes

OBJECTIVES

To review the proposed mechanisms of cognitive changes associated with non-central nervous system cancers and cancer treatment.

DATA SOURCES

Review and synthesis of databased publications and review articles.

CONCLUSION

Proposed mechanisms include cytokine upregulation, hormonal changes, neurotransmitter dysregulation, attentional fatigue, genetic predisposition, and comorbid symptoms.

IMPLICATIONS FOR NURSING PRACTICE

Oncology nurses need to understand the multiple mechanisms that may contribute to the development of cancer- and treatment-related cognitive changes so that they can identify patients at high risk and help patients understand why these changes occur.

Ovarian cycle effects on immediate reward selection bias in humans: a role for estradiol

A variety of evidence suggests that, among humans, the individual tendency to choose immediate rewards ("Now") over larger, delayed rewards ("Later"), or Now bias, varies with frontal dopamine (DA) levels. As cyclic elevations in estradiol (E+) modulate other frontal DA-dependent behaviors, we tested ovarian cycle effects on Now bias, and whether any such effects are E+ mediated. To do so, we quantified Now/Later choice behavior in naturally cycling adult females (n = 87; ages 18-40 years) during both the menstrual phase (MP; cycle day 1-2; low E+), and the follicular phase (FP; cycle day 11-12; high E+). Now bias decreased an average of 3.6% from MP to FP (p = 0.006). Measures of salivary E+ levels at each visit were available in a subsample of participants (n = 34). Participants with a verified E+ rise from MP to FP showed significantly greater decreases in Now bias at mid-cycle (n = 23) than those without a rise (n = 11; p = 0.03); Now bias decreased an average of 10.2% in the E+ rise group but increased an average of 7.9% in the no E+ rise group. The change in Now bias from MP to FP inversely correlated with the change in E+ (ρ = -0.39; p = 0.023), an effect driven by individuals with putatively lower frontal DA based on genotype at the Val(158)Met polymorphism in the COMT gene. This is the first demonstration that intertemporal choice varies across the ovarian cycle, with Now bias declining at mid-cycle, when fertility peaks. Moreover, our data suggest that the interacting effects of estradiol and frontal DA mediate this cycle effect on decision making.

Longitudinal assessment of cognitive changes associated with adjuvant treatment for breast cancer: the impact of APOE and smoking

PURPOSE

This study examined the association of post-treatment changes in cognitive performance, apolipoprotein E (APOE), and smoking in breast cancer patients treated with adjuvant therapy.

PARTICIPANTS AND METHODS

Breast cancer patients treated with chemotherapy (N = 55, age = 51.9 ± 7.1, education = 15.7 ± 2.6) were evaluated with a battery of neuropsychological tests prior to chemotherapy and at 1, 6, and 18 months post-chemotherapy. Matched groups of breast cancer patients not exposed to chemotherapy (N = 68, age = 56.8 ± 8.3, education = 14.8 ± 2.2) and healthy controls (N = 43, age = 53.0 ± 10.1, education = 15.2 ± 2.6) were evaluated at similar intervals. APOE epsilon 4 carrier status (APOE4+) and smoking history were also evaluated.

RESULTS

The detrimental effect of APOE4+ genotype on post-treatment cognitive functioning was moderated by smoking history, that is, patients without a smoking history had significantly lower performance on measures of processing speed and working memory compared with those with a smoking history and healthy controls. Exploratory analyses revealed that APOE4+ patients without a smoking history who were exposed to chemotherapy showed a decline in performance in processing speed, compared with patients with a smoking history. A similar but less pronounced pattern was seen in the no chemotherapy group (primarily endocrine treatment). For working memory, the APOE4+ by smoking interaction was observed in the no chemotherapy group only.

CONCLUSIONS

The association between APOE status, breast cancer treatment, and cognitive functioning was moderated by smoking history suggesting that both chemotherapy and endocrine therapy interact with APOE status and smoking to influence cognition. A putative mechanism is that smoking corrects a deficit in nicotinic receptor functioning and dopamine levels in APOE4+ individuals.

Intra-individual variability in women with breast cancer

Studies assessing cognitive functioning in women treated for breast cancer have used primarily standardized neuropsychological tests and examined accuracy and/or reaction time as outcome measures: they have been inconsistent in identifying the cognitive domains affected and the severity of deficits. In other contexts of neural development and disorders, measures of Intra-individual variability (IIV) have proven useful in identifying subtleties in performance deficits that are not captured by measures of central tendency. This article presents proof of concept that assessing IIV may also increase understanding of the cognitive effects of cancer treatment. We analyzed mean accuracy and reaction time, as well as IIV from 65 women with breast cancer and 28 age and education matched controls who performed the Conner's Continuous Performance Test, a "Go-NoGo" task. Although there were no significant differences between groups using measures of central tendency, there was a group × inter-stimulus interval (ISI) interaction for IIV Dispersion (p < .001). Patient Dispersion was more variable at shorter ISI than controls and less variable at long ISI, suggesting greater sensitivity to presentation speed. Interpretation of IIV differences requires further investigation. Our results suggest that future studies would benefit from designs that allow analysis of IIV measures in studies assessing cognition in cancer survivors.

Prevalence, mechanisms, and management of cancer-related cognitive impairment

This review summarizes the current literature on cancer-related cognitive impairment (CRCI) with a focus on prevalence, mechanisms, and possible interventions for CRCI in those who receive adjuvant chemotherapy for non-central nervous system tumours and is primarily focused on breast cancer. CRCI is characterized as deficits in areas of cognition including memory, attention, concentration, and executive function. Development of CRCI can impair quality of life and impact treatment decisions. CRCI is highly prevalent; these problems can be detected in up to 30% of patients prior to chemotherapy, up to 75% of patients report some form of CRCI during treatment, and CRCI is still present in up to 35% of patients many years following completion of treatment. While the trajectory of CRCI is becoming better understood, the mechanisms underlying the development of CRCI are still obscure; however, host characteristics, immune dysfunction, neural toxicity, and genetics may play key roles in the development and trajectory of CRCI. Intervention research is limited, though strategies to maintain function are being studied with promising preliminary findings. This review highlights key research being conducted in these areas, both in patient populations and in animals, which will ultimately result in better understanding and effective treatments for CRCI.

Association between variants of 5-hydroxytryptamine receptor 3C (HTR3C) and chemotherapy-induced symptoms in women receiving adjuvant treatment for breast cancer

Administration of chemotherapy is associated with a wide array of symptoms affecting quality of life. Genetic risk factors for severity of chemotherapy-induced symptoms have not been determined. The present study aimed to explore the associations between polymorphisms in candidate genes and chemotherapy-induced symptoms. Women treated with at least two cycles of adjuvant doxorubicin and cyclophosphamide, with or without paclitaxel for early breast cancer (n = 105) completed the memorial symptom assessment scale and provided blood for genotyping. DNA was extracted from peripheral blood leukocytes and assayed for single nucleotide polymorphisms (SNPs) in GTP cyclohydrolase 1 (GCH1, rs10483639, rs3783641, and rs8007267), catecholamine-o-methyltransferase (COMT, rs4818), and 5-hydroxytryptamine (serotonin) receptor 3C (HTR3C, rs6766410, and rs6807362). Genotyping of HTR3C revealed a significant association between the presence of rs6766410 and rs6807362 SNPs (K163 and G405 variants) and increased severity of symptoms (p = 0.0001 and p = 0.007, respectively). Multiple regressions revealed that rs6766410 and rs6807362, but not age or stage at diagnosis, predicted severity of symptoms (p = 0.001 and p = 0.006, respectively) and explained 12 % of the variance in each regression model. No association was found between the genetic variants of CGH1 or COMT and symptom score. Our study indicates, for the first time, an association between variants of HTR3C and severity of chemotherapy-induced symptoms. Analyzing these genetic variants may identify patients at increased risk for the development of chemotherapy-induced symptoms and targeting the serotonin pathway may serve as a novel treatment strategy for these patients.

Investigating the relationship between COMT polymorphisms and working memory performance among childhood brain tumor survivors

BACKGROUND

Survivors of childhood brain tumors are at increased risk for neurocognitive impairments, including deficits in abilities supported by frontal brain regions. Catechol-O-methyltransferase (COMT) metabolizes dopamine in the prefrontal cortex, with the Met allele resulting in greater dopamine availability and better performance on frontally mediated tasks compared to the Val allele. Given the importance of identifying resiliency factors against the emergence of cognitive late effects, the current study examined the relationship between COMT genotype and working memory performance among childhood brain tumor survivors.

PROCEDURE

Children treated for a brain tumor with conformal radiation therapy (N = 50; mean age at irradiation = 7.41 ± 3.41; mean age at assessment = 13.18 ± 2.88) were administered two computerized measures of working memory (self-ordered search verbal and object tasks). Buccal (cheek) swabs were used to provide tissue from which DNA was extracted.

RESULTS

Findings revealed an association between COMT genotype and performance on the self-ordered verbal (P = 0.03) but not object task (P = 0.33). Better performance was found for the Met/Val group compared to either Met/Met or Val/Val.

CONCLUSIONS

COMT may indicate a potential resiliency factor against neurocognitive effects of cancer and its treatment; however, there is a need for replication with larger samples of childhood brain tumor survivors.