Cognitive effects of chemotherapy in post-menopausal breast cancer patients 1 year after treatment

Status of adjuvant endocrine therapy for breast cancer

Adjuvant endocrine therapy reduces the risk of recurrence and death from breast cancer in women with hormone receptor-positive early breast cancer. Tamoxifen has been the standard therapy for decades, and this is still the case for pre-menopausal women. Ovarian suppression is of similar efficacy but currently there is no strong evidence for adding this to tamoxifen and the additional morbidity can be considerable. Results from two important trials addressing this issue are imminent. In post-menopausal women, aromatase inhibitors (AIs) (letrozole, anastrozole, or exemestane) are superior to tamoxifen in preventing recurrence but only letrozole has been shown to improve survival. The main gain is against high-risk cancers, and tamoxifen gives very similar benefit for low-risk disease. Traditionally, treatment has been given for around 5 years, but many women remain at risk of relapse for 10 years or more. The AIs, and more recently tamoxifen, have been shown to reduce further the risk of late recurrence in women still in remission after 5 years of tamoxifen if given for a further 5 years. The comparative benefits of these two options and the selection of patients most likely to benefit from long-term adjuvant endocrine therapy are important topics for further research, as is the optimum duration of AI therapy started upfront.

Chemotherapy altered brain functional connectivity in women with breast cancer: a pilot study

Adjuvant chemotherapy is associated with improvements in long-term cancer survival. However, reports of cognitive impairment following treatment emphasize the importance of understanding the long-term effects of chemotherapy on brain functioning. Cognitive deficits found in chemotherapy patients suggest a change in brain functioning that affects specific cognitive domains such as attentional processing and executive functioning. This study examined the processes potentially underlying these changes in cognition by examining brain functional connectivity pre- and post-chemotherapy in women with breast cancer. Functional connectivity examines the temporal correlation between spatially remote brain regions in an effort to understand how brain networks support specific cognitive functions. Nine women diagnosed with breast cancer completed a functional magnetic resonance imaging (fMRI) session before chemotherapy, 1 month after, and 1 year after the completion of chemotherapy. Seed-based functional connectivity analyses were completed using seeds in the intraparietal sulcus (IPS) to examine connectivity in the dorsal anterior attention network and in the posterior cingulate cortex (PCC) to examine connectivity in the default mode network. Results showed decreased functional connectivity 1 month after chemotherapy that partially returned to baseline at 1 year in the dorsal attention network. Decreased connectivity was seen in the default mode network at 1 month and 1 year following chemotherapy. In addition, increased subjective memory complaints were noted at 1 month and 1 year post-chemotherapy. These findings suggest a detrimental effect of chemotherapy on brain functional connectivity that is potentially related to subjective cognitive assessment.

The association between pro-inflammatory cytokines, regional cerebral metabolism, and cognitive complaints following adjuvant chemotherapy for breast cancer

To examine relationships following adjuvant chemotherapy between circulating pro-inflammatory cytokines, regional cerebral metabolism, and cognitive complaints in early stage breast cancer patients. 33 breast cancer patients who had completed initial treatment (surgery, ± radiation, 23 chemotherapy, 10 no chemotherapy) obtained resting (18)F-FDG PET/CT brain imaging at baseline and 1 year later. Pro-inflammatory cytokine markers (IL-1ra, sTNF-RII, CRP, and IL-6) and cognitive complaints were also assessed at both time points. At baseline, consistent correlations were seen between the left medial frontal and right inferior lateral anterior temporal cortices and inflammatory markers within the chemotherapy group, and not in the no chemotherapy group. After 1 year, correlations persisted in the medial frontal cortex and the temporal cortex, the latter shifting superiorly. Both of these regional correlations demonstrated the highest levels of significance when looking across the 1 year time frame (IL-1ra: peak voxel p < 0.0005; cluster size p < 0.0005, p = 0.001 after correction (medial prefrontal), p < 0.0005; cluster size p = 0.001, p = 0.029 corr. (anterior temporal), sTNF-RII: p < 0.0005; cluster size p = 0.001, p = 0.040 corr. (medial prefrontal)). Positive correlations were also seen within the chemotherapy group between baseline memory complaints and the medial frontal (p < 0.0005; cluster size p < 0.0005, p < 0.0005 corr.) and anterior temporal (p < 0.0005; cluster size p < 0.0005, p = 0.002 corr.) cortices at baseline and 1 year later. Metabolism in the medial prefrontal cortex and anterior temporal cortex was found to correlate with both memory complaints and cytokine marker levels in chemotherapy patients.

Memory and cancer: a review of the literature

The mental health of cancer survivors has not always been the primary emphasis of treatment protocols since physical health outcomes have taken precedence. Older cancer survivors experience a double jeopardy since they are at risk for memory impairments and mild cognitive impairment and because they are greater than 55 years of age. Of the 9.6 million cancer survivors in the US who have completed active treatment, many report cognitive difficulties, with labels such as "chemo brain," "not as sharp," "woolly-headedness," or the "mind does not work as quickly". To date, most of our knowledge of cognitive impairment in cancer survivors comes from female breast cancer survivors. Studies indicate that these survivors have diminished executive function, verbal memory, and motor function. Cancer survivors want to live independently in the community for as long as possible however, these cognitive deficits may prevent this desired lifestyle. To broaden our understanding this paper reviews the literature on the cognitive impairment and memory deficits experienced by three groups of cancer survivors breast, colorectal, and prostate cancer, that make up 60% of all survivors nationally. Even though mental health declined after a cancer diagnosis, the long-term outcomes of cancer survivors did not differ from persons without cancer in depression or cognitive function.

Altered cerebral blood flow one month after systemic chemotherapy for breast cancer: a prospective study using pulsed arterial spin labeling MRI perfusion

Cerebral structural and functional alterations have been reported after chemotherapy for non-CNS cancers, yet the causative mechanism behind these changes remains unclear. This study employed a novel, non-invasive, MRI-based neuroimaging measure to provide the first direct longitudinal measurement of resting cerebral perfusion in breast cancer patients, which was tested for association with changes in cognitive function and gray matter density. Perfusion was measured using pulsed arterial spin labeling MRI in women with breast cancer treated with (N = 27) or without (N = 26) chemotherapy and matched healthy controls (N = 26) after surgery before other treatments (baseline), and one month after chemotherapy completion or yoked intervals. Voxel-based analysis was employed to assess perfusion in gray matter; changes were examined in relation to overall neuropsychological test performance and frontal gray matter density changes measured by structural MRI. Baseline perfusion was not significantly different across groups. Unlike control groups, chemotherapy-treated patients demonstrated significantly increased perfusion post-treatment relative to baseline, which was statistically significant relative to controls in the right precentral gyrus. This perfusion increase was negatively correlated with baseline overall neuropsychological performance, but was not associated with frontal gray matter density reduction. However, decreased frontal gray matter density was associated with decreased perfusion in bilateral frontal and parietal lobes in the chemotherapy-treated group. These findings indicate that chemotherapy is associated with alterations in cerebral perfusion which are both related to and independent of gray matter changes. This pattern of results suggests the involvement of multiple mechanisms of chemotherapy-induced cognitive dysfunction. Additionally, lower baseline cognitive function may be a risk factor for treatment-associated perfusion dysregulation. Future research is needed to clarify these mechanisms, identify individual differences in susceptibility to treatment-associated changes, and further examine perfusion change over time in survivors.

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.

Persistent cognitive changes in breast cancer patients 1 year following completion of chemotherapy

Numerous studies have shown that there are acute cognitive side-effects of chemotherapy for breast cancer. Presumably, patients are more concerned about chronic treatment effects. This report from a prospective longitudinal study compares cognitive functioning in 56 breast cancer patients 1 year after chemotherapy to that of 56 healthy individuals. Neuropsychological test scores were combined into verbal memory, visual memory, working memory, and processing speed scores, as well as an overall summary score, and analyzed using multi-level growth modeling. Frequency of cognitive decline was assessed using regression-based change scores. There was significant rebound in the overall summary score from end of treatment to 1-year follow-up as well as a substantial reduction in the frequency of cognitive decline. However, more than one-third of the breast cancer patients who showed cognitive decline immediately following completion of chemotherapy showed persistent cognitive decline 1 year later. Furthermore, recovery was not seen in all cognitive domains. In fact, the rebound was significant only for working memory. Longer multi-site studies are recommended to explore the risk factors for and the permanence of these longer-term cognitive effects.

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.

[Aspects of encephalopathy in oncologic patients after chemotherapy]

OBJECTIVE

To study clinical presentations and neuroimaging results in post chemotherapy encephalopathy.

MATERIAL AND METHODS

We examined 27 patients with cancer after chemotherapy (n=16) or chemoradiation (n=11).

RESULTS AND CONCLUSION

All patients complained of memory impairment, sluggish mentality, moderate headache, fatigue, sleep disorder, irritability. Their neurologic status included different organic symptoms. Post chemotherapy encephalopathy is characterized by the combination of severe cerebral asthenia and different organic neurologic symptoms with moderate cephalgic syndrome. MRT showed single and multiple loci of gliosis in the white matter.

Clearing the air: a review of our current understanding of "chemo fog"

An increasing number of cancer survivors has led to a greater interest in the long-term side effects of cancer treatments and their impact on quality of life. In particular, cognitive impairments have been frequently reported by cancer survivors as an adverse effect which they attribute to the neurotoxicity of chemotherapy and have dubbed "chemobrain" or "chemo fog." Research within the past 15-20 years has explored the many factors thought to contribute to cancer-related cognitive decline in an attempt to determine a potential cause. In spite of many confounding factors, there is growing evidence that the neurotoxicity of chemotherapy does contribute to cognitive changes. This review examines the evolution of "chemo fog" research with a look at methodological issues, the status of our current understanding, and suggestions for future research.

[A meta-analysis of chemotherapy related cognitive impairment in patients with breast cancer]

PURPOSE

The purpose of this study was to evaluate the cognitive effects of chemotherapy in patients with breast cancer.

METHODS

Using several databases, prospective studies were collected up to August 2011. Of 2,106 publications identified, 12 met the inclusion criteria, and 8 studies were used to estimate the effect size of chemotherapy on cognitive impairment.

RESULTS

Twelve studies were done since 2005 and most of the research was performed in Europe or North America. Eight studies were used to generate effect size across the cognitive domains of attention/concentration, verbal and visual memory, executive function, visuospatial skill, language, and subjective cognitive function. Each of the cognitive domains showed small effect sizes (-0.02 ~ -0.26), indicating diminished cognitive function for the chemotherapy group compared with non-chemotherapy groups.

CONCLUSION

Finding suggests that breast cancer patients who undergo chemotherapy may experience mild cognitive decline. Further study is needed to generate knowledge and guideline for interventions to address chemotherapy related cognitive impairment in these patients.

New approaches to understand cognitive changes associated with chemotherapy for non-central nervous system tumors

CONTEXT

Researchers have described a constellation of cognitive deficits (e.g., impairments in executive functions, working memory, attention, and information-processing speed) associated with cancer treatment, and specifically chemotherapy, for non-central nervous system tumors. However, findings have been inconsistent, largely because of measurement and study design issues.

OBJECTIVES

To propose ways for researchers to more clearly delineate and characterize the mild cognitive deficits and related outcomes that appear to affect a subset of cancer patients and suggest methods to make more effective use of the existing data to understand risk factors for impaired neuropsychological functioning.

METHODS

We examined the literature on the relationship between chemotherapy and cognitive impairment, as well as related literature on neuropsychological measurement, structural and functional neuroimaging, alternative measures of health outcomes, and integrative data analysis.

RESULTS

A more comprehensive picture of cognitive functioning might be obtained by incorporating nontraditional ecological measures, self-reports, computational modeling, new neuroimaging methods, and markers of occupational functioning. Case-control and integrative data analytic techniques potentially could leverage existing data to identify risk factors for cognitive dysfunction and test hypotheses about the etiology of these effects.

CONCLUSION

There is a need to apply new research approaches to understand the real-world functional implications of the cognitive side effects of chemotherapy to develop and implement strategies to minimize and remediate these effects before, during, and after cancer treatment.

Quality of Life in Long-Term Breast Cancer Survivors

Purpose

There is considerable interest in the quality of life (QOL) of long-term breast cancer (BC) survivors. We studied changes in QOL from time of BC diagnosis to long-term survivorship and compared QOL in long-term survivors to that of age-matched women with no history of BC.

Patients and Methods

In all, 535 women with localized BC (T1-3N0-1M0) were recruited from 1989 to 1996 and followed prospectively, completing QOL questionnaires at diagnosis and 1 year postdiagnosis. Between 2005 and 2007, those alive without distant recurrence were recontacted to participate in a long-term follow-up (LTFU) study. A control group was recruited from women presenting for screening mammograms, and both groups completed LTFU QOL questionnaires. Longitudinal change in BC survivors and differences between BC survivors and controls were assessed in eight broad categories with clinically significant differences set at 5% and 10% of the breadth of each QOL scale.

Results

A total of 285 patients with BC were included in the study, on average 12.5 years postdiagnosis. Longitudinally, clinically significant improvements were observed in overall QOL by 1 year postdiagnosis with further improvements by LTFU. Some clinically significant improvements over time were seen in all categories. A total of 167 controls were recruited. Deficits were observed in self-reported cognitive functioning (5.3% difference) and financial impact (6.3% difference) in BC survivors at LTFU compared with controls.

Conclusion

Long-term BC survivors show improvement in many domains of QOL over time, and they appear to have similar QOL in most respects to age-matched noncancer controls, although small deficits in cognition and finances were identified.

Cognitive change and neuroimaging following immunoablative therapy and hematopoietic stem cell transplantation in multiple sclerosis: A pilot study

BACKGROUND

Individuals with MS undergoing immunoablative therapy and hematopoietic stem cell transplantation (HSCT) show substantial decrease in brain volume over 2.4 months, presumably from chemotoxic effects, although other mechanisms have also been postulated.

OBJECTIVE

We examined whether volume loss was accompanied by a concomitant decrease in cognition. White and gray matter volumes, and the effect of stem cell dosage were considered.

METHODS

Seven individuals with rapidly progressing MS and poor prognosis underwent high dose immunosuppression and autologous HSCT. Neuropsychological testing and MRI scans were performed at baseline, 2 and 24 months post-procedure.

RESULTS

Cognitive impairment was noted at all times in most participants. Median decline of 1.39% in total brain volume was noted 2 months post-HSCT. By 24 months a further decline of 1.65% was noted. At 2 months significant decline was observed for areas of executive functioning. At 24 months almost no significant declines were noted. No significant correlations were found between cognitive decline and change in imaging variables or stem cell dosage.

CONCLUSIONS

Cognition changed in the early period following treatment but with little apparent relationship to volume changes. With temporal distance from the HSCT procedure, cognition returned to baseline levels. With the caution of a very small sample, preliminary results suggest that immunoablation and HSCT may have no lasting deleterious effects on cognition.

A pilot study of prospective memory functioning in early breast cancer survivors

AIMS

To evaluate prospective memory (PM) functioning in early breast cancer (BC) survivors and its association with fatigue and depression.

METHODS

The Memory for Intention Screening Test, the Center for Epidemiologic Studies Depression Scale and the Functional Assessment of Cancer Therapy-Fatigue subscale were administered to 80 patients and 80 aged-matched healthy controls.

RESULTS

Patients performed more poorly than controls on the memory test (p < 0.001) and had a higher rate of impairment (odds ratio = 5.5, p < 0.01). Fatigue mediated the relationship between Group membership and PM performance.

CONCLUSIONS

BC survivors exhibited a clear pattern of PM deficit and fatigue was a major contributor to this deficit. This suggests that a common mechanism may be involved in fatigue symptoms and memory disturbances experienced by patients. Further research is needed to evaluate the role of adjuvant therapy in PM deficits and to explore whether interventions targeted at improving fatigue may also improve memory functioning in BC survivors.

Multivariate analysis of brain metabolism reveals chemotherapy effects on prefrontal cerebellar system when related to dorsal attention network

BACKGROUND

Functional brain changes induced by chemotherapy are still not well characterized. We used a novel approach with a multivariate technique to analyze brain resting state [18 F]FDG-PET in patients with lymphoma, to explore differences on cerebral metabolic glucose rate between chemotherapy-treated and non-treated patients.

METHODS

PET/CT scan was performed on 28 patients, with 14 treated with systemic chemotherapy. We used a support vector machine (SVM) classification, extracting the mean metabolism from the metabolic patterns, or networks, that discriminate the two groups. We calculated the correct classifications of the two groups using the mean metabolic values extracted by the networks.

RESULTS

The SVM classification analysis gave clear-cut patterns that discriminate the two groups. The first, hypometabolic network in chemotherapy patients, included mostly prefrontal cortex and cerebellar areas (central executive network, CEN, and salience network, SN); the second, which is equal between groups, included mostly parietal areas and the frontal eye field (dorsal attention network, DAN). The correct classification membership to chemotherapy or not chemotherapy-treated patients, using only one network, was of 50% to 68%; however, when all the networks were used together, it reached 80%.

CONCLUSIONS

The evidenced networks were related to attention and executive functions, with CEN and SN more specialized in shifting, inhibition and monitoring, DAN in orienting attention. Only using DAN as a reference point, indicating the global frontal functioning before chemotherapy, we could better classify the subjects. The emerging concept consists in the importance of the investigation of brain intrinsic networks and their relations in chemotherapy cognitive induced changes.

Opening up the window into "chemobrain": a neuroimaging review

As more chemotherapy-treated cancer patients are reaching survivorship, side-effects such as cognitive impairment warrant research attention. The advent of neuroimaging has helped uncover a neural basis for these deficits. This paper offers a review of neuroimaging investigations in chemotherapy-treated adult cancer patients, discussing the benefits and limitations of each technique and study design. Additionally, despite the assumption given by the chemobrain label that chemotherapy is the only causative agent of these deficits, other factors will be considered. Suggestions are made on how to more comprehensively study these cognitive changes using imaging techniques, thereby promoting generalizability of the results to clinical applications. Continued investigations may yield better long-term quality of life outcomes by supporting patients' self-reports, and revealing brain regions being affected by chemotherapy.

Frontal gray matter reduction after breast cancer chemotherapy and association with executive symptoms: a replication and extension study

Cognitive changes related to cancer and its treatment have been intensely studied, and neuroimaging has begun to demonstrate brain correlates. In the first prospective longitudinal neuroimaging study of breast cancer (BC) patients we recently reported decreased gray matter density one month after chemotherapy completion, particularly in frontal regions. These findings helped confirm a neural basis for previously reported cognitive symptoms, which most commonly involve executive and memory processes in which the frontal lobes are a critical component of underlying neural circuitry. Here we present data from an independent, larger, more demographically diverse cohort that is more generalizable to the BC population. BC patients treated with (N=27) and without (N=28) chemotherapy and matched healthy controls (N=24) were scanned at baseline (prior to systemic treatment) and one month following chemotherapy completion (or yoked intervals for non-chemotherapy and control groups) and APOE-genotyped. Voxel-based morphometry (VBM) showed decreased frontal gray matter density after chemotherapy, as observed in the prior cohort, which was accompanied by self-reported difficulties in executive functioning. Gray matter and executive symptom changes were not related to APOE ε4 status, though a somewhat greater percentage of BC patients who received chemotherapy were ε4 allele carriers than patients not treated with chemotherapy or healthy controls. These findings provide confirmatory evidence of frontal morphometric changes that may be a pathophysiological basis for cancer and treatment-related cognitive dysfunction. Further research into individual risk factors for such changes will be critical for development of treatment and prevention strategies.

The effect of systemic chemotherapy on neurogenesis, plasticity and memory

Chemotherapy has been enormously successful in treating many forms of cancer and improving patient survival rates. With the increasing numbers of survivors, a number of cognitive side effects have become apparent. These have been called "chemobrain" or "chemofog" among patient groups, who describe the symptoms as a decline in memory, concentration and executive functions. Changes which, although subtle, can cause significant distress among patients and prevent a return to the quality of life experienced before treatment. This cognitive side effect of chemotherapy was not anticipated as it had been assumed that chemotherapy agents, administered systematically, could not cross the blood-brain barrier and that the brain was therefore protected from their action. It is now realised that low concentrations of many chemotherapy agents cross the blood-brain barrier and even those that are completely prevented from doing so, can induce the production of inflammatory cytokines in peripheral tissues which in turn can cross the blood-brain barrier and impact on the brain. A large number of patient studies have shown that cognitive decline is found in a proportion of patients treated with a variety of chemotherapy agents for different types of cancer. The deficits experienced by these patients can last for up to several years and have a deleterious effect on educational attainment and ability to return to work. Imaging studies of patients after systemic chemotherapy show that this treatment produces structural and functional changes in the brain some of which seem to persist even when the cognitive deficits have ceased. This suggests that, with time, brain plasticity may be able to compensate for the deleterious effects of chemotherapy treatment. A number of mechanisms have been suggested for the changes in brain structure and function found after chemotherapy. These include both central and peripheral inflammatory changes, demyelination of white matter tracts, a reduction in stem cell proliferation in both the hippocampal neurogenic region and by oligodendrocyte precursors as well as changes in hormonal or growth factor levels. A number of possible treatments have been suggested which range from pharmacological interventions to cognitive behavioural therapies. Some of these have only been tested in animal models while others have produced varying degrees of improvement in patient populations. Currently, there is no recognised treatment and a greater understanding of the causes of the cognitive decline experienced after chemotherapy will be key to finding ways of preventing or treating the effects of chemobrain.

A meta-analysis of the effects of chemotherapy on cognition in patients with cancer

OBJECTIVE

The aim of this meta-analysis was to assess whether chemotherapy-related cognitive impairment is consistently observed in cancer patients and to identify the areas of cognition affected.

METHODS

The meta-analysis included 13 studies and examined the effects of chemotherapy on seven different cognitive domains, across five cancer types. It was the intention of this meta-analysis to stringently exclude many studies, allowing for examination of cognition in carefully selected studies of chemotherapy recipients who do not have current mood or anxiety diagnoses (or psychiatric or substance abuse histories), without brain cancer and who have not had radiotherapy or hormone treatment. A moderator analysis examined whether patient age, treatment duration and time since treatment end significantly contributed to chemotherapy-related cognitive impairment.

RESULTS

Evidence for the presence of cognitive impairment following cancer treatment was established for executive function and memory. No relationship was found between cognitive impairment and time since treatment cessation but a significant negative relationship was found for treatment duration. Age had no impact on treatment-related cognitive impairment.

CONCLUSIONS

Future research must be conducted on chemotherapy-related cognitive impairment in cancer types such as lymphoma and leukaemia, which have received a moderate amount of attention and colorectal cancer, which has received little attention. This would enable us to determine the extent to which chemotherapy-related cognitive impairment is a universal phenomenon associated with the cancer experience and its treatment regardless of cancer type.

Brain vulnerability to chemotherapy toxicities

Chemotherapy-induced cognitive changes have been an increasing concern among cancer survivors. By using adjuvant treatment for breast cancer as the prototype, this manuscript reviews research from neuropsychological, imaging, genetic, and animal model studies that have examined the clinical presentation and potential mechanisms for cognitive changes associated with exposure to chemotherapy. An impressive body of research supports the hypothesis that a subgroup of patients is vulnerable to post-treatment cognitive changes, although not exclusively related to chemotherapy. Further, imaging and animal model studies provide accumulating evidence of putative mechanisms for chemotherapy-induced cognitive change. Models of aging are also reviewed in support of the proposal that cognitive changes associated with cancer and cancer treatments can be viewed in the context of factors that affect the trajectory of normal aging.

Cancer- and cancer treatment-associated cognitive change: an update on the state of the science

Cognitive changes associated with cancer and cancer treatments have become an increasing concern. Using breast cancer as the prototype, we reviewed the research from neuropsychological, imaging, genetic, and animal studies that have examined pre- and post-treatment cognitive change. An impressive body of research supports the contention that a subgroup of patients is vulnerable to post-treatment cognitive problems. We also propose that models of aging may be a useful conceptual framework for guiding research in this area and suggest that a useful perspective may be viewing cognitive change in patients with cancer within the context of factors that influence the trajectory of normal aging.

Chemotherapy-related cognitive dysfunction

Many cancer patients develop treatment-related cognitive dysfunction that affects their quality of life and can result in diminished functional independence. There is an emerging body of transdisciplinary research demonstrating that chemotherapeutic agents can produce neurobiological changes within the brain, which are associated with a constellation of cognitive changes that can result in decreased quality of life and functional independence. The increased incidence of cancer, coupled with longer survival times, has resulted in larger numbers of cancer survivors who are struggling with this neurotoxicity. This review summarizes the neuropsychological findings in patients with breast and brain cancer who receive systemic chemotherapy as well as the recent animal and imaging research elucidating the mechanisms by which these therapies impact brain structure, function, and consequent behavior.

Meta-analysis of cognitive functioning in breast cancer survivors previously treated with standard-dose chemotherapy

PURPOSE

Evidence is mixed regarding long-term cognitive deficits in patients treated with chemotherapy. Previous meta-analyses have not focused specifically on the postchemotherapy period and have not incorporated several recent studies. The goal of the current study was to conduct a meta-analysis of cognitive functioning in breast cancer survivors who were treated with chemotherapy ≥ 6 months previously.

METHODS

A search of PubMed, PsycInfo, Cumulative Index to Nursing and Allied Health Literature, and Cochrane Library yielded 2,751 abstracts, which were independently evaluated by pairs of raters. Meta-analysis was conducted on 17 studies of 807 patients previously treated with standard-dose chemotherapy for breast cancer. Neuropsychological tests were categorized according to eight cognitive domains: attention, executive functioning, information processing, motor speed, verbal ability, verbal memory, visual memory, and visuospatial ability.

RESULTS

Deficits in cognitive functioning were observed in patients treated with chemotherapy relative to controls or prechemotherapy baseline in the domains of verbal ability (g = -0.19; P < .01) and visuospatial ability (g = -0.27; P < .01). Patients treated with chemotherapy performed worse than noncancer controls in verbal ability and worse than patients treated without chemotherapy in visuospatial ability (both P < .01). Age, education, time since treatment, and endocrine therapy did not moderate observed cognitive deficits in verbal ability or visuospatial ability (all P ≥ .51).

CONCLUSION

Results indicate that, on average, observed cognitive deficits in patients with breast cancer previously treated with chemotherapy are small in magnitude and limited to the domains of verbal ability and visuospatial ability. This information can be used to inform interventions to educate patients with breast cancer regarding the long-term impact of chemotherapy on cognitive functioning.

Doxorubicin: an update on anticancer molecular action, toxicity and novel drug delivery systems

Objectives

The frontline drug doxorubicin has been used for treating cancer for over 30 years. While providing a cure in select cases, doxorubicin causes toxicity to most major organs, especially life-threatening cardiotoxicity, which forces the treatment to become dose-limiting.

Key findings

Doxorubicin is known to bind to DNA-associated enzymes, intercalate with DNA base pairs, and target multiple molecular targets to produce a range of cytotoxic effects. For instance, it causes the activation of various molecular signals from AMPK (AMP-activated protein kinase inducing apoptosis) to influence the Bcl-2/Bax apoptosis pathway. By altering the Bcl-2/Bax ratio, downstream activation of different caspases can occur resulting in apoptosis. Doxorubicin also induces apoptosis and necrosis in healthy tissue causing toxicity in the brain, liver, kidney and heart. Over the years, many studies have been conducted to devise a drug delivery system that would eliminate these adverse affects including liposomes, hydrogel and nanoparticulate systems, and we highlight the pros and cons of these drug delivery systems.

Summary

Overall the future for the continued use of doxorubicin clinically against cancer looks set to be prolonged, provided certain enhancements as listed above are made to its chemistry, delivery and toxicity. Increased efficacy depends on these three aims being met satisfactorily as discussed in turn in this review.

Alterations in brain structure and function after chemotherapy for cancer

The majority of cancer patients treated with chemotherapy complain of fatigue and/or cognitive dysfunction. Although many patients experience improvement shortly after completion of treatment, a substantial number of patients may continue to be symptomatic for years or even decades after their last dose of chemotherapy. This review focuses on the scope of postchemotherapy cognitive dysfunction, spotlights recent studies that investigate this problem in the short- and long-term, examines neuroimaging studies that document regional cerebral alterations observed after chemotherapy, discusses candidate mechanisms and treatments and finally comments on challenges in the field.

Alterations in brain activation during working memory processing associated with breast cancer and treatment: a prospective functional magnetic resonance imaging study

PURPOSE

To prospectively examine alterations in working memory (WM) -associated brain activation related to breast cancer and treatment by using functional magnetic resonance imaging.

PATIENTS AND METHODS

Patients treated with chemotherapy (CTx+; n = 16) or without chemotherapy (CTx-; n = 12) and healthy controls (n = 15) were scanned during an n-back task at baseline (after surgery but before radiation, chemotherapy, and/or antiestrogen treatment), 1 month after completion of chemotherapy (M1), and 1 year later (Y1), or at yoked intervals for CTx- and controls. SPM5 was used for all image analyses, which included cross-sectional between-group and group-by-time interaction and longitudinal within-group analyses, all using a statistical threshold of 0.001.

RESULTS

At baseline, patients with cancer showed increased bifrontal and decreased left parietal activation compared with controls. At M1, both cancer groups showed decreased frontal hyperactivation compared with controls, with increased hyperactivation at Y1. These cross-sectional findings were confirmed by group-by-time interaction analyses, which showed frontal activation decreases from baseline to M1 in patients compared with controls. Within-group analyses showed different patterns of longitudinal activation change by treatment group (CTx+ or CTx-), with prominent alterations in the frontal lobes bilaterally.

CONCLUSION

Significant frontal lobe hyperactivation to support WM was found in patients with breast cancer. Superimposed on this background, patients showed decreased frontal activation at M1, with partial return to the previously abnormal baseline at Y1. These functional changes correspond to frontal lobe regions where we previously reported structural changes in this cohort and provide prospective, longitudinal data that further elucidate mechanisms underlying cognitive effects related to breast cancer and its treatment.

An evaluation on the neuropsychological tests used in the assessment of postchemotherapy cognitive changes in breast cancer survivors

OBJECTIVES

The choice of appropriate neuropsychological tests is important in evaluating the onset, severity, duration, and site of cognitive changes in postchemotherapy breast cancer survivors. This literature review is designed to evaluate and provide a summary of suitable neuropsychological tests to determine cognitive changes in breast cancer survivors.

METHOD

A literature search restricted to publications in English before June 2011 was performed using the following combination of keywords: "neuropsychological assessments," "breast cancer," "chemotherapy," and "cognitive impairment." Only observational studies that performed cognitive assessments on breast cancer survivors were included. The neuropsychological assessments were grouped as "objective" (traditional batteries and screening tests), "subjective," or "computerized."

RESULTS

Of the 43 studies extracted, memory (88 %) and attention/concentration (88 %) are the two most commonly assessed domains. A majority (63 %) employed the use of Wechsler Adult Intelligent Scale (an objective test), while only 49 % incorporated subjective assessments to assess perceived cognitive impairment. Computerized tests received low popularity (28 %) despite their numerous advantages, which include overcoming the language- and cultural-dependent limitations of traditional objective tests.

CONCLUSIONS

In the selection of a suitable neuropsychological tool to determine the onset, severity, site, and duration of cognitive changes in breast cancer survivors, incorporation of both subjective and objective tests is essential to facilitate a comprehensive assessment. With more validation work performed in future studies, it may be feasible to employ computerized neuropsychological assessments in both clinical and research settings.

Experiences of Changes in Cognitive Function for Women treated with Chemotherapy for Breast Cancer

PURPOSE

The purpose of this study was to describe the experiences of the process of the change in cognitive function for women treated with chemotherapy for breast cancer.

METHODS

There were ten participants in total in this study. Data were gathered utilizing in-depth interviews over 3 times from September 2010 to January 2011. Data were analyzed by employing Strauss and Corbin's (1998) grounded theory methodology.

RESULTS

Findings indicate that causal conditions of these results were 'side effects of chemotherapy' and 'menopausal state', including contextual conditions as, 'mental fatigue' and 'anxiety about recurrence'. The core category was identified as 'confronting with unexpected chaos'. Intervening conditions were 'support from other people', 'lack of information on cognitive impairment'. Interaction strategies were 'changing the habit of life', 'making efforts for living life' and 'seeking for medical information'. Consequences of the process were 'physical restriction', 'difficulty in social life', 'disturbed working ability' and 'psychological distress'.

CONCLUSION

The results of this study show that nurses should recognize there is a notable difference between individual patient's contextual conditions and interactive strategies. Furthermore educational information and individualized intervention should be provided to improve cognitive function for women with breast cancer.

Neuropsychological performance in survivors of breast cancer more than 20 years after adjuvant chemotherapy

PURPOSE

Adjuvant chemotherapy for breast cancer can have adverse effects on cognition shortly after administration. Whether chemotherapy has any long-term effects on cognition is largely unknown, yet it becomes increasingly relevant because of the widespread use of chemotherapy for early-stage breast cancer and the improved survival. We investigated whether cyclophosphamide, methotrexate, and fluorouracil (CMF) chemotherapy for breast cancer is associated with worse cognitive performance more than 20 years after treatment.

PATIENTS AND METHODS

This case-cohort study compared the cognitive performance of patients with breast cancer who had a history of adjuvant CMF chemotherapy treatment (six cycles; average time since treatment, 21 years; n = 196) to that of a population-based sample of women never diagnosed with cancer (n = 1,509). Participants were between 50 and 80 years of age. Exclusion criteria were ever use of adjuvant endocrine therapy, secondary malignancy, recurrence, and/or metastasis.

RESULTS

The women exposed to chemotherapy performed significantly worse than the reference group on cognitive tests of immediate (P = .015) and delayed verbal memory (P = .002), processing speed (P < .001), executive functioning (P = .013), and psychomotor speed (P = .001). They experienced fewer symptoms of depression (P < .001), yet had significantly more memory complaints on two of three measures that could not be explained by cognitive test performance.

CONCLUSION

Survivors of breast cancer treated with adjuvant CMF chemotherapy more than 20 years ago perform worse, on average, than random population controls on neuropsychological tests. The pattern of cognitive problems is largely similar to that observed in patients shortly after cessation of chemotherapy. This study suggests that cognitive deficits following breast cancer diagnosis and subsequent CMF chemotherapy can be long lasting.

Longitudinal assessment of chemotherapy-induced structural changes in cerebral white matter and its correlation with impaired cognitive functioning

PURPOSE

To uncover the neural substrate of cognitive impairment related to adjuvant chemotherapy, we studied cerebral white matter (WM) integrity before and after chemotherapy by using magnetic resonance diffusion tensor imaging (DTI) in combination with detailed cognitive assessment.

PATIENTS AND METHODS

Thirty-four young premenopausal women with early-stage breast cancer who were exposed to chemotherapy underwent neuropsychologic testing and DTI before the start of chemotherapy (t1) and 3 to 4 months after treatment (t2). Sixteen patients not exposed to chemotherapy and 19 age-matched healthy controls underwent the same assessment at matched intervals. In all groups, we used paired t tests to study changes in neuropsychologic test scores and whole-brain voxel-based paired t tests to study changes in WM fractional anisotropy (FA; a DTI measure that reflects WM tissue organization), with depression scores and intelligence quotient as included covariates. We correlated changes of neuropsychologic test scores with the mean change of FA for regions that survived the paired t tests in patients treated with chemotherapy.

RESULTS

In contrast to controls, the chemotherapy-treated group performed significantly worse on attention tests, psychomotor speed, and memory at t2 compared with t1 (P < .05). In the chemotherapy-treated group, we found significant decreases of FA in frontal, parietal, and occipital WM tracts after treatment (familywise error P < .05), whereas for both control groups, FA values were the same between t1 and t2. Furthermore, performance changes in attention and verbal memory correlated with mean regional FA changes in chemotherapy-treated patients (P < .05).

CONCLUSION

We report evidence of longitudinal changes in cognitive functioning and cerebral WM integrity after chemotherapy as well as an association between both.

Cognitive functioning after cancer treatment: a 3-year longitudinal comparison of breast cancer survivors treated with chemotherapy or radiation and noncancer controls

BACKGROUND

This study examined the influence of prior treatment on the course of cognitive functioning in breast cancer survivors. Changes in cognitive functioning over time were compared in breast cancer survivors treated with chemotherapy plus radiotherapy, breast cancer survivors treated with radiotherapy only, and women with no history of cancer.

METHODS

Stage 0-II breast cancer patients treated with chemotherapy plus radiotherapy (CT group; n = 62) or radiotherapy only (RT group; n = 67) completed neuropsychological assessments 6 months after completing treatment and again 36 months later. Women with no history of cancer (NC group; n = 184) were assessed over a similar interval.

RESULTS

A significant group × time effect was found for processing speed (P = .009) that reflected a tendency for the NC group but not the RT and CT groups to improve over time. There was also a significant group effect for executive functioning (P = .006) that reflected the NC group performing better than the CT and RT groups. Additional analyses found the administration of hormonal therapy was not associated with change over time in cognitive performance.

CONCLUSIONS

Findings provide limited support for the view that changes in cognitive functioning in cancer survivors are attributable to chemotherapy administration and illustrate the importance of including a radiotherapy comparison group. Future research should seek to examine possible mechanisms that could explain the apparent prolonged impact of both chemotherapy and radiotherapy on cognitive functioning in breast cancer survivors.

Neuro-cognitive impairment in breast cancer patients: pharmacological considerations

Post-chemotherapy cognitive impairment has been an issue of concern in cancer survivors. While most reviews are focused on patient-related factors, it is proposed that drug-related factors may also be determinants. The objective of this review is to study the relationship between the types and dose intensities of chemotherapy regimens on cognitive impairment in breast cancer patients through a systematic literature search. Eighteen prospective studies were selected. The types, dose intensities and durations of chemotherapy regimens received by subjects were compared against prevalence results obtained in individual studies. It was observed that the duration of impairment varied across different generations of chemotherapy regimens. Concurrent administration of multiple cytotoxic agents can lead to a synergistic decline on cognition. Current clinical evidence is insufficient to evaluate the relationship between the types, dose intensities of chemotherapy regimens and cognitive impairment. More investigation is needed to examine the role of pharmacological factors in chemotherapy-associated cognitive changes.

Effects of adjuvant treatment on cognitive function in women with early breast cancer

PURPOSE

Whether adjuvant therapy impairs cognitive function in women with breast cancer (BC) is unclear. We determined the effects of adjuvant therapy on cognitive function in women with early BC.

METHODS

We consecutively and prospectively enrolled women aged 40-69 years who had a positive radiographic finding from the mammography screening program at Stockholm South General Hospital. All women completed the Headminder Web-based neuropsychological battery Cognitive Stability Index (CSI) for response speed, processing speed, memory, and attention before diagnosis (T1), after surgery and before adjuvant treatment (T2), 6 months after start of adjuvant treatment (T3), and after another 3 months of follow-up (T4). Women with BC were divided into those receiving chemotherapy, hormone therapy, or no adjuvant medical therapy. Women without a diagnosis of BC served as healthy controls.

RESULTS

Of the 146 women enrolled, 77 had BC of whom 18 received chemotherapy; 45, hormone therapy, and 14, no adjuvant medical therapy; 69 were healthy controls. Memory scores for women with BC were significantly lower than those for controls over time, even after controlling for age and education. Memory and response speed scores were lower after chemotherapy than before (P<0.01 for both). Processing speed and attention improved significantly over time in all groups, a result consistent with a practice effect.

CONCLUSION

Our results indicate subtle changes related to time course and treatment. Especially, that chemotherapy may impair memory and response speed in women with BC, consistent with those reported by BC survivors after adjuvant medical treatment.

Changes in perceived attentional function in women following breast cancer surgery

After treatment for breast cancer, many women experience cognitive problems, as determined by objective neuropsychological tests. However, the ecological validity of these tests has been questioned. This study explored the trajectory of perceived attentional function from before to 24 months after surgery in women with breast cancer and examined the effect of adjuvant treatment on this perceived attentional function. Women with breast cancer (N = 200) were assessed for perceived cognitive function by measuring attentional function using the attentional function index (AFI). Covariates included anxiety, depression, fatigue, and sleep disturbance. Perceived attentional function declined in 54% of women at 1 month after surgery. At 1 and 2 years after surgery, 41 and 30% of women, respectively, still perceived this decline. The mean AFI decreased to the lowest point 1 month after surgery, but improved gradually afterward, taking about 1 year to return to the pre-surgery level. Decreases in perceived attentional function were associated with increases in anxiety, depression, fatigue, and sleep disturbance. After controlling for baseline differences and covariates, mean AFI scores were not associated with adjuvant treatment. Perceived cognitive function deteriorated after surgery but improved over time. It was not associated with adjuvant cancer treatment.

An update on cancer- and chemotherapy-related cognitive dysfunction: current status

The purpose of this review is to summarize the current literature on the effects of cancer treatment-related cognitive difficulties, with a focus on the effects of chemotherapy. Numerous patients have cognitive difficulties during and after cancer treatments and, for some, these effects last years after treatment. We do not yet fully understand which factors increase susceptibility to cognitive difficulties during treatment and which cause persistent problems. We review possible contributors, including genetic and biological factors. Mostly we focus is on cognitive effects of adjuvant chemotherapy for breast cancer; however, cognitive effects of chemotherapy on the elderly and brain tumor patients are also discussed.

Cognitive dysfunction and cancer: which consequences in terms of disease management?

OBJECTIVES

The aim of this review is to stress the importance of cognitive dysfunction in cancer survivors, and to discuss the way of assessing and managing these troubles in clinical practice.

METHOD

Original studies and reviews reporting the effect of cancer and chemotherapy on cognition and published since January 2000 were selected from the Medline(®) database using 'cognition' or 'cognitive function' and 'cancer' as subject headings.

RESULTS

Main reports concerned women with advanced breast cancer or children with hematological or brain cancers. Overall, chemotherapy was found to be associated with subtle and transient cognitive dysfunctions, which were detectable only with neuropsychological testing and affected most particularly memory, concentration and speed of information processing. Some factors associated with the patient, like depression, may favor cognitive impairment, while the role of others, like age or educational level, remains to be defined. Screening of patients at risk remains limited due to the lack of standardized neuropsychological tests in clinical oncology practice. Few studies have addressed the benefits of interventional strategies but methylphenidate, modafinil and erythropoietin, as well as rehabilitation in children, have shown encouraging results. Formal studies assessing the value of a multidisciplinary approach to detect and manage cognitive impairment must be recommended.

CONCLUSION

Cognitive dysfunction induced by cancer or the treatment represents a real challenge in clinical practice. Based on limited published data, few clinical recommendations can be made regarding prevention, evaluation and management of this trouble. Longitudinal studies must be conducted to evaluate its real impact on quality of life.

Aromatase inhibitor therapy: toxicities and management strategies in the treatment of postmenopausal women with hormone-sensitive early breast cancer

Aromatase inhibitors (AIs) have been shown to reduce the risk of breast cancer recurrence and are widely used today as adjuvant therapy in women with early stage endocrine-responsive breast cancer. Aromatase inhibitors may be prescribed as initial hormonal therapy, sequentially following 2-3 years of tamoxifen, or as extended adjuvant therapy (following 5 years of tamoxifen). Aromatase inhibitors are generally well tolerated; however, certain side effects, particularly arthralgia/musculoskeletal symptoms and gynecologic effects, may result in poor adherence to treatment. Patients receiving adjuvant therapy with an AI should be counseled regarding possible side effects and the importance of completing treatment. Interventions to ameliorate side effects should be individualized based on symptoms, comorbid conditions, and pre-existing therapies. In addition, bone and cardiovascular health should be monitored during AI therapy. Prompt therapeutic management of common side effects associated with AIs may provide patients with the opportunity to receive the full benefit of their adjuvant hormonal treatment while minimizing toxicity.

Impact of liposomal doxorubicin-based adjuvant chemotherapy on autonomy in women over 70 with hormone-receptor-negative breast carcinoma: A French Geriatric Oncology Group (GERICO) phase II multicentre trial

RATIONALE

Breast cancer is a disease of ageing. Functional independence in elderly patients, measured with the Katz activities of daily living (ADL) scale, predicts overall survival and the need for welfare support. Few prospective studies have examined the feasibility of adjuvant chemotherapy and its impact on autonomy in women over 70 years of age with high-risk breast cancer. This multicentre phase II trial was designed to assess the impact of adjuvant anthracycline-based chemotherapy on these patients' autonomy.

DESIGN AND METHODS

In a two-stage Fleming design, women aged ≥70 years with histologically proven hormone-receptor-negative early breast cancer and a significant risk of recurrence (pN+ or "high risk" pN0) received 4 cycles of nonpegylated liposomal doxorubicin 60 mg/m(2) and cyclophosphamide 600 mg/m(2) every 3 weeks postoperatively, on an outpatient basis. The primary endpoint was the change in the ADL score during chemotherapy. Secondary endpoints include comprehensive geriatric, quality-of-life and acceptability assessments, tolerability, and long-term outcome. The results for the primary endpoint and other scales at completion of adjuvant chemotherapy are reported here, while long-term follow-up is not yet complete.

RESULTS

Forty patients (median age 75 [70-82]) were enrolled between February 2006 and November 2007. Chemotherapy had no deleterious impact on ADL, cognition, mental status, or the frequency of comorbidities. In contrast, the number of patients at risk of malnutrition, based on the Mini Nutritional Assessment, more than doubled between baseline and the end of chemotherapy, rising from 15% to 38%. Quality-of-life deteriorated in terms of social and role functioning, likely owing to fatigue, loss of appetite, nausea and vomiting. Treatment acceptability was good. The main adverse effect was neutropenia, 15% of the patients experiencing febrile neutropenia. No cardiac toxicity or toxic deaths occurred.

CONCLUSION

This study demonstrates the feasibility of an adjuvant chemotherapy regimen combining nonpegylated liposomal doxorubicin and cyclophosphamide in fit elderly women <85 years with breast cancer. Although chemotherapy had an impact on social and role functioning, autonomy was not impaired and toxicity was acceptable. Special attention should be paid to nutritional status before and after treatment.

It's not over when it's over: long-term symptoms in cancer survivors--a systematic review

BACKGROUND

The number of cancer survivors is steadily increasing. Following completion of primary cancer treatment and many years thereafter, specific symptoms continue to negatively affect cancer survivors. The purpose of this article is to review the evidence of symptom burden following primary treatment for cancer in survivors of the most common types of cancer (breast, gynecological, prostate, and colorectal).

METHODS

A systematic review of literature published between the years 2000-2008 that reported late-effects and/or long-term psychosocial symptoms associated with cancer survivorship post-completion of primary cancer treatment was conducted. The symptoms include physical limitations, cognitive limitations, depression/anxiety, sleep problems, fatigue, pain, and sexual dysfunctions.

RESULTS

Symptom burden associated with cancer survivorship was consistent among the four most common types of cancer (breast, gynecological, prostate, and rectal/colon), despite various types of treatment exposure. Generally, across the cancer groups, depressive symptoms, pain, and fatigue were commonly found in cancer survivors.

CONCLUSIONS

Based on longitudinal and cross-sectional evidence, cancer survivors can experience symptoms for more than 10 years following treatment. These symptoms were present in survivors of all four cancer types who underwent a wide variety of treatment. The results indicate that these symptoms should be evaluated and managed to optimize long-term outcomes.