Neurophysiological evaluation of late effects of adjuvant high-dose chemotherapy on cognitive function

Chemo brain (chemo fog) as a potential side effect of doxorubicin administration: role of cytokine-induced, oxidative/nitrosative stress in cognitive dysfunction

Doxorubicin (ADRIAMYCIN, RUBEX) is a chemotherapeutic agent that is commonly administered to breast cancer patients in standard chemotherapy regimens. As true of all such therapeutic cytotoxic agents, it can damage normal, noncancerous cells and might affect biochemical processes in a manner that might lead to, or contribute to, chemotherapy-induced cognitive deficits when administered either alone or in combination with other agents.

Systemic administration of doxorubicin impairs aversively motivated memory in rats

There is growing clinical evidence of cognitive impairment in cancer patients treated with chemotherapy, especially in women treated with drug combinations for breast cancer. Clinical studies have a difficult task of defining which drugs individually are responsible for the cognitive changes and published papers evaluating single agents in experimental models are scanty. In the present study we have investigated the effect of single escalating doses of doxorubicin (DOX) on memory for inhibitory avoidance conditioning (IA) in rats. The doses used were comparable to those applied in the clinic. When given systemically before training, higher doses of DOX impaired IA memory retention measured 24h and 7days, but not 3h after training. DOX did not affect IA retention when given either before or after training in a multiple-trial IA training protocol. Control experiments showed that DOX produced a decrease in exploratory behavior assessed by the number of rearings performed during exploration of an open field. The results indicate that a single systemic administration of DOX might impair long-term aversive learning.

Cognitive speed of processing and functional declines in older cancer survivors: an analysis of data from the ACTIVE trial

It has been suggested that chemotherapy treatment for cancer may contribute to cognitive decline in older cancer survivors. This issue is particularly important given that subtle cognitive impairment, particularly in cognitive processing speed, can affect functional status and quality of life for older adults. Multivariate regression of data from a longitudinal randomized controlled trial of older adults revealed a trend towards decreased performance after cancer treatment with chemotherapy on several functional measures associated with processing speed (as compared with matched individuals who did not have cancer). Additional analyses revealed that a subset of the chemotherapy-treated adults demonstrated a reliable negative change on several measures of processing speed. While inconclusive, this hypothesis generating work suggests that cognitive dysfunction following cancer treatment may contribute to disability observed in older cancer survivors. Further research is needed to determine the significance of the relationship between cognitive and functional impairment in older cancer survivors.

Cognitive Effects of Systemic Therapy in Patients with Breast Cancer

Many patients with breast cancer complain about concentration and memory problems in connection with systemic therapy. A number of studies investigating the possible decrease in cognitive abilities were published in the 1980s. Numerous studies showed impaired performance of patients receiving chemotherapy. The results concerning profile, extent, and duration of cognitive impairments are, however, non-uniform. Increasing interest has been focused in the last years on effects of endocrine therapy on cognitive capacity - especially concerning the effects of the almost complete estrogen depletion caused by aromatase inhibitors. Often, the published studies did not evaluate particular effects of endocrine therapy without considering interference of cytotoxic treatment. Furthermore, the different endocrine medications (antiestrogens vs. aromatase inhibitors) were usually not regarded separately despite different mechanisms of action. Hence, the results of past investigations are also controversial. In the future, prospective trials with larger samples are necessary. Differentiation between chemotherapy and endocrine therapy is essential. Likewise, different types of endocrine therapy should be examined separately.

Cancer, cognitive impairment, and meditation

BACKGROUND AND OBJECTIVES

Cancer-related cognitive impairment has been acknowledged as a substantial limiting factor in quality of life among cancer patients and survivors. In addition to deficits on behavioral measures, abnormalities in neurologic structure and function have been reported. In this paper, we review findings from the literature on cognitive impairment and cancer, potential interventions, meditation and cognitive function, and meditation and cancer. In addition, we offer our hypotheses on how meditation practice may help to alleviate objective and subjective cognitive function, as well as the advantages of incorporating a meditation program into the treatment of cancer patients and survivors for cancer-related cognitive deficits.

FINDINGS

Various factors have been hypothesized to play a role in cancer-related cognitive impairment including chemotherapy, reduced hormone levels, proinflammatory immune response, fatigue, and distress. Pharmacotherapies such as methylphenidate or modafinil have been suggested to alleviate cognitive deficits. While initial reports suggest they are effective, some pharmacotherapies have side effects and may not relieve other symptoms associated with multimodal cancer treatment including sleep disturbance, nausea and pain. Several recent studies investigating the effects of meditation programs have reported behavioral and corresponding neurophysiological modulations that may be particularly effective in alleviating cancer-related cognitive impairment. Such programs also have been shown to reduce stress, fatigue, nausea and pain, and improve mood and sleep quality.

CONCLUSIONS

With the increasing success of cancer treatment and the ability to return to previous family, social, and work activities, symptom management and quality of life are an essential part of survivorship. We propose that meditation may help to improve cancer-related cognitive dysfunction, alleviate other cancer-related sequelae, and should be fully investigated as an adjuvant to cancer treatment.

Prophylactic cranial irradiation in advanced breast cancer: a case for caution

PURPOSE

Prophylactic cranial irradiation (PCI) has a well-recognized role in the treatment of leukemia and small-cell lung cancer. Clinical utility has yet to be determined for breast cancer, where an emerging group at high risk of brain metastasis has fuelled consideration of PCI.

METHODS AND MATERIALS

In reviewing our experience with PCI as part of a complex protocol for advanced breast cancer, we present descriptive data on late central nervous system outcomes in those receiving PCI. After high-dose anthracycline-based induction chemotherapy, Stage IIIB/IV breast cancer responders underwent tandem autologous marrow transplantation. Those in continued remission were referred for PCI. Whole-brain radiotherapy was delivered by usual means, at 36 Gy in 20 fractions.

RESULTS

Twenty-four women, with median age 45 (28-61), were enrolled between 1995 and 1998. Disease was largely metastatic (79%), and 75% were previously exposed to chemotherapy or hormonotherapy. Ten patients received PCI, at a median of 13.4 (11.8-16.5) months from study entry. Six patients developed brain metastases, 2 despite PCI. Striking functional decline was documented in 3 patients (at 9 months, 4 years, and 5 years post-PCI), including one previously high-functioning woman requiring full care for posttreatment dementia.

CONCLUSIONS

We present a series of advanced breast cancer patients treated prophylactically with whole-brain radiotherapy following an aggressive chemotherapy regimen. Although the therapeutic benefit of PCI is not ascertainable here, we describe brain metastases occurring despite PCI and serious long-term neurobehavioral sequelae in PCI-treated patients. Any further investigation of PCI in high-risk breast cancer will need to be approached with caution.

A novel electrophysiological model of chemotherapy-induced cognitive impairments in mice

PURPOSE

Chemotherapeutic agents are known to produce persistent cognitive deficits in cancer patients. However, little progress has been made in developing animal models to explore underlying mechanisms and potential therapeutic interventions. We report an electrophysiological model of chemotherapy-induced cognitive deficits using a sensory gating paradigm, to correspond with performance in two behavioral tasks.

EXPERIMENTAL DESIGN

Mice received four weekly injections of methotrexate and 5-fluorouracil. Whole-brain event-related potentials (ERPs) were recorded throughout using a paired-click paradigm. Mice underwent contextual fear conditioning (CFC) and novel-object recognition testing (NOR).

RESULTS

Chemotherapy-treated animals showed significantly impaired gating 5 weeks after drug treatments began, as measured by the ratio of the first positive peak in the ERP (P1) minus the first negative peak (N1) between first and second auditory stimuli. There was no effect of drug on the amplitude of P1-N1 or latency of P1. The drug-treated animals also showed significantly increased freezing during fear conditioning and increased exploration without memory impairment during novel object recognition.

CONCLUSIONS

Chemotherapy causes decreased ability to gate incoming auditory stimuli, which may underlie associated cognitive impairments. These gating deficits were associated with a hyperactive response to fear conditioning and reduced adaptation to novel objects, suggesting an additional component of emotional dysregulation. However, amplitudes and latencies of ERP components were unaffected, as was NOR performance, highlighting the subtle nature of these deficits.

Effects of chemotherapeutic agents 5-fluorouracil and methotrexate alone and combined in a mouse model of learning and memory

RATIONALE

The concern that adjuvant cancer chemotherapy agents cause cognitive impairment in a significant number of patients has been expressed by patients and healthcare providers, but clinical studies have yielded conflicting results to date.

OBJECTIVE

We directly tested two commonly used chemotherapeutic agents in a mouse model of learning and memory.

MATERIALS AND METHODS

In the present study, mice were conditioned to respond for a liquid reinforcer (Ensure solution) in the presence of an audible tone on day 1 as a measure of acquisition and were then required to perform the same response on day 2 as a measure of retrieval and retention. Methotrexate and 5-fluorouracil were administered prior to the day 1 session.

RESULTS

Methotrexate (1.0-32 mg/kg) alone failed to alter mean latency acquisition, retrieval, or reinforced response rates. Similar to scopolamine, a known amnesic in this assay, 5-fluorouracil (3-75 mg/kg) failed to alter response rates or acquisition latency on day 1 but significantly altered latency to retrieve a previously learned response on day 2. In combination, 3.2 mg/kg methotrexate plus 75 mg/kg 5-fluorouracil significantly increased day 1 and day 2 acquisition and retrieval latencies without altering response rates or motivation to respond as measured by progressive ratio responding.

CONCLUSION

Taken together, these data demonstrate that 5-fluorouracil causes increased latencies for retrieval of previously learned behavioral responses and that combination of chemotherapeutic agents may produce greater delays than either agent alone, including when neither agent alone does so.

Persistent neurocognitive problems after adjuvant chemotherapy for breast cancer

BACKGROUND

Neurocognitive problems have been observed in a number of women previously treated with adjuvant chemotherapy for breast cancer. The present study aims to combine the results of neuropsychological and electrophysiological techniques collected in patients with breast cancer treated with cyclophosphamide/methotrexate/5-fluorouracil (CMF) at different time points.

PATIENTS AND METHODS

Patients with breast cancer treated with adjuvant CMF chemotherapy (n = 63) were examined with neuropsychological tests 1 year after treatment and compared with healthy women (n = 60; T1 portion of the study). Based on neuropsychological test performance, patients were classified as cognitively impaired or unimpaired. Four years later, behavioral and neurophysiological measures (T2 portion of the study) were collected during an information-processing task in a subgroup of patients (n = 26). At T2, we compared the results of cognitively impaired patients (n = 8) with those of patients classified as cognitively unimpaired at T1 (n = 18).

RESULTS

In the initial neuropsychological assessment, 33.3% of the patients were classified as cognitively impaired, compared with 10% of healthy women. At T2, impaired patients who received CMF showed longer P3 latencies, lower P3 amplitudes, longer reaction times, and made more errors in an information processing task compared with unimpaired patients who received CMF.

CONCLUSION

The results indicate the persistence of neurocognitive problems < or = 5 years after completion of chemotherapy and consistency across different assessment techniques.

Systemic 5-fluorouracil treatment causes a syndrome of delayed myelin destruction in the central nervous system

BACKGROUND

Cancer treatment with a variety of chemotherapeutic agents often is associated with delayed adverse neurological consequences. Despite their clinical importance, almost nothing is known about the basis for such effects. It is not even known whether the occurrence of delayed adverse effects requires exposure to multiple chemotherapeutic agents, the presence of both chemotherapeutic agents and the body's own response to cancer, prolonged damage to the blood-brain barrier, inflammation or other such changes. Nor are there any animal models that could enable the study of this important problem.

RESULTS

We found that clinically relevant concentrations of 5-fluorouracil (5-FU; a widely used chemotherapeutic agent) were toxic for both central nervous system (CNS) progenitor cells and non-dividing oligodendrocytes in vitro and in vivo. Short-term systemic administration of 5-FU caused both acute CNS damage and a syndrome of progressively worsening delayed damage to myelinated tracts of the CNS associated with altered transcriptional regulation in oligodendrocytes and extensive myelin pathology. Functional analysis also provided the first demonstration of delayed effects of chemotherapy on the latency of impulse conduction in the auditory system, offering the possibility of non-invasive analysis of myelin damage associated with cancer treatment.

CONCLUSIONS

Our studies demonstrate that systemic treatment with a single chemotherapeutic agent, 5-FU, is sufficient to cause a syndrome of delayed CNS damage and provide the first animal model of delayed damage to white-matter tracts of individuals treated with systemic chemotherapy. Unlike that caused by local irradiation, the degeneration caused by 5-FU treatment did not correlate with either chronic inflammation or extensive vascular damage and appears to represent a new class of delayed degenerative damage in the CNS.

Somatic chronic diseases and 6-year change in cognitive functioning among older persons

The influence of seven highly prevalent somatic chronic diseases on changes in cognitive functioning is investigated in older persons in a prospective design covering a 6-year follow-up period. The data were collected as part of the Longitudinal Aging Study Amsterdam (LASA). The associations between chronic diseases and cognitive functioning during 6 years of follow-up were analyzed among 1358 respondents (age 62-85) using generalized estimated equations (GEE). Cognitive tests were used to assess: general cognitive functioning, fluid intelligence, information processing speed and memory performance. In the fully adjusted models diabetes mellitus, stroke and peripheral artherosclerosis were associated with cognitive decline during a 6-year follow-up period in older persons. In the unadjusted models cardiac disease was negatively associated with memory function. However, after the correction for possible confounders this association became positive. Cancer was also associated with better memory function. A faster decline in especially memory function was found for diabetes mellitus, stroke, cancer, and peripheral artherosclerosis. The study shows that in older persons specific chronic diseases (diabetes mellitus, stroke, cancer, and peripheral artherosclerosis) are associated with decline in one or more domains of cognitive functioning during a 6-year follow-up period. These findings further stress that careful clinical evaluation of cognitive functioning in older persons with these diseases is required in order to provide adequate care.

Major depression after breast cancer: a review of epidemiology and treatment

OBJECTIVE

While many breast cancer patients experience "normal" distress, there is a subset who experience clinically significant depression. We examined the current knowledge about the prevalence, impact and treatment of major depression in women with breast cancer.

METHOD

We reviewed the evidence for the prevalence of depression in women with breast cancer from the last 20 years and summarized the medical literature on the pharmacology and psychotherapy of depression in this population.

RESULTS

Despite evidence that depression significantly impacts quality of life in breast cancer patients, few studies focus on the epidemiology and treatment of major depression. Treatment studies have focused on distress and mixed depressive states, with resulting lack of replicable studies showing treatment efficacy. Potential biological and psychosocial determinants of major depression following breast cancer are discussed in a proposed model. The need for further research on the epidemiology and treatment of major depression in this population is proposed.

CONCLUSION

Major depression is a frequent but underrecognized and undertreated condition among breast cancer patients, which causes amplification of physical symptoms, increased functional impairment and poor treatment adherence. More research on the epidemiology and treatment of major depression in this population is needed.

Cognitive function after chemotherapy in adults with solid tumours

BACKGROUND

Evidence is emerging that some cancer survivors suffer cognitive impairment after chemotherapy; the cause is unknown.

METHODS

Here we review studies evaluating cognitive impairment in adult cancer survivors and discuss methodological challenges associated with this research. We evaluate evidence for cognitive impairment in cancer patients, the incidence of self-reported impairment, and identify potential mechanisms and confounders.

RESULTS

Most studies of cognitive function are cross-sectional and report impairment in 15-45% of subjects. Longitudinal studies suggest that some impairment is present prior to receiving chemotherapy, and that this worsens in some patients. The aetiology is unknown. A larger number of subjects self-report changes in cognitive function after chemotherapy; this does not correlate with objective testing.

CONCLUSIONS

Cognitive impairment occurs in a subset of cancer survivors and is generally subtle. Most evidence suggests an association with chemotherapy although other factors associated with the diagnosis and treatment of cancer may contribute.

Chemotherapy-Related Change in Cognitive Function: A Conceptual Model

PURPOSE/OBJECTIVES

To develop a conceptual model of chemotherapy-related changes in cognitive function.

DATA SOURCES

MEDLINE, CINAHL, HealthStar, and PsycINFO databases.

DATA SYNTHESIS

Patients undergoing chemotherapy often complain of forgetfulness, absentmindedness, and an inability to focus when performing a variety of daily tasks. Changes in cognitive function have been referred to by the colloquial term "chemo-brain." The authors conducted an examination of the literature to investigate relationships among concepts and to synthesize current knowledge.

CONCLUSIONS

Cognitive function, defined as higher-order mental processes, may be altered along two distinct and interacting pathways: (a) the cancer diagnosis, which can lead to anxiety, stress, distress, and depression; and (b) the direct physiologic effects of cancer treatment. The Chemotherapy-Related Change in Cognitive Function conceptual model is informed by a review of literature that illustrates antecedents, moderators, mediators, and consequences that may be relevant to this issue.

IMPLICATIONS FOR NURSING

When a patient presents with cognitive complaints, the problems can be evaluated for intervention when an overall understanding exists of chemotherapy-related cognitive changes based on a conceptual model that continues to be informed through well-conceptualized and well-designed research.

Neurologic toxicities of cancer therapies

Neurologic dysfunction is a well-recognized adverse effect of cancer therapeutics. The most common manifestations include peripheral neuropathy and encephalopathy. Often, symptoms resolve or improve upon removal of the offending agent; therefore, it is essential that clinicians recognize the symptoms and signs of injury. Occasionally, symptoms persist or develop after discontinuation of medication and may culminate in disability and diminished quality of life. As our understanding of neurotoxicity improves, medications with less potential for injury may be developed. In addition, potential antidotes to prevent or reverse injury may emerge. This review focuses on the clinical features, mechanisms, and possible therapeutics of the neurotoxicity of chemotherapy. In particular, oxaliplatin, thalidomide, methotrexate, ifosfamide, cytarabine, amifostine, acetyl-L-carnitine, methylene blue, cytokines, and neurotrophins are discussed.

DNA repair in neurons: so if they don't divide what's to repair?

Neuronal DNA repair remains one of the most exciting areas for investigation, particularly as a means to compare the DNA repair response in mitotic (cancer) vs. post-mitotic (neuronal) cells. In addition, the role of DNA repair in neuronal cell survival and response to aging and environmental insults is of particular interest. DNA damage caused by reactive oxygen species (ROS) such as generated by mitochondrial respiration includes altered bases, abasic sites, and single- and double-strand breaks which can be prevented by the DNA base excision repair (BER) pathway. Oxidative stress accumulates in the DNA of the human brain over time especially in the mitochondrial DNA (mtDNA) and is proposed to play a critical role in aging and in the pathogenesis of several neurological disorders including Parkinson's disease, ALS, and Alzheimer's diseases. Because DNA damage accumulates in the mtDNA more than nuclear DNA, there is increased interest in DNA repair pathways and the consequence of DNA damage in the mitochondria of neurons. The type of damage that is most likely to occur in neuronal cells is oxidative DNA damage which is primarily removed by the BER pathway. Following the notion that the bulk of neuronal DNA damage is acquired by oxidative DNA damage and ROS, the BER pathway is a likely area of focus for neuronal studies of DNA repair. BER variations in brain aging and pathology in various brain regions and tissues are presented. Therefore, the BER pathway is discussed in greater detail in this review than other repair pathways. Other repair pathways including direct reversal, nucleotide excision repair (NER), mismatch repair (MMR), homologous recombination and non-homologous end joining are also discussed. Finally, there is a growing interest in the role that DNA repair pathways play in the clinical arena as they relate to the neurotoxicity and neuropathy associated with cancer treatments. Among the numerous side effects of cancer treatments, major clinical effects include neurocognitive dysfunction and peripheral neuropathy. These symptoms occur frequently and have not been effectively studied at the cellular or molecular level. Studies of DNA repair may help our understanding of how those cells that are not dividing could succumb to neurotoxicity with the clinical manifestations discussed in the following article.

Glutathione elevation by γ-glutamyl cysteine ethyl ester as a potential therapeutic strategy for preventing oxidative stress in brain mediated by in vivo administration of adriamycin: Implication for chemobrain

Oxidative stress in heart and brain by the cancer chemotherapeutic drug adriamycin (ADR), used for treating solid tumors, is well established. Long-term treatment with ADR in breast cancer patients has led to symptoms of cardiomyopathy. Less well recognized, but increasingly well documented, is cognitive dysfunction. After chemotherapy, free radical-mediated oxidative stress has been reported in both heart and brain. We recently showed a significant increase in protein oxidation and lipid peroxidation in brain isolated from mice injected intraperitonially (i.p) with ADR. Systemic administration of ADR also induces tumor necrosis factor-alpha (TNF-alpha), which leads to production of reactive oxygen species (ROS) and reactive nitrogen species (RNS) in brain. Circulating TNF also causes mitochondrial dysfunction, leading to apoptotic pathways in brain. Inducible nitric oxide synthase also plays a role in ADR-induced TNF-mediated neurotoxicity. In addition, we previously showed a significant decrease in glutathione (GSH) levels in brain isolated from ADR injected mice, along with increased expression of multidrug-resistant protein-1 (MRP-1), glutathione-S-transferase (GST), glutathione peroxidase (GPx), and glutathione reductase (GR). There was a significant decrease in activity of brain GST. The present study was designed to test the hypothesis that, by elevating brain levels of GSH, the brain would be protected against oxidative stress in ADR-injected mice. gamma-Glutamyl cysteine ethyl ester (GCEE), a precursor of glutathione, injected i.p. (150 mg/ kg body weight) 4 hr prior ADR injection (20 mg/kg body weight) led to significantly decreased protein oxidation and lipid peroxidation in subsequently isolated mice brain compared with brain isolated from ADR-injected mice without GCEE. The GSH levels were restored to the level of brain isolated from saline-injected mice. Furthermore, the enzyme activity of GST was increased in brain isolated from ADR-injected mice previously injected with GCEE compared with the brain isolated from ADR-injected mice previously injected with saline. These results are discussed with regard to potential pharmacological prevention of brain cognitive dysfunction in patients receiving ADR chemotherapy.

Effects of high-dose and conventional-dose adjuvant chemotherapy on long-term cognitive sequelae in patients with breast cancer: an electrophysiologic study

BACKGROUND

The mechanisms underlying cognitive deficits found in a number of patients with breast cancer treated with adjuvant chemotherapy are still unclear. In the current study, we used a combination of measures of brain electric activity and cognitive performance during information processing to elucidate the origin of these cognitive deficits.

PATIENTS AND METHODS

Twenty-nine patients at high risk with breast cancer treated with adjuvant conventional-dose cyclophosphamide/epirubicin/5-fluorouracil or adjuvant high-dose cyclophosphamide/thiotepa/carboplatin were compared with 23 patients with stage I breast cancer not treated with chemotherapy approximately 4 years after completion of treatment. We studied reaction times and the amplitudes and latencies of the P3, an electrophysiologic index of information processing, in a task with different conditions related to input, central, and output processing of information.

RESULTS

The amplitude of the P3 component was significantly reduced in patients with breast cancer treated with high-dose cyclophosphamide/thiotepa/carboplatin compared with patients with breast cancer not treated with chemotherapy. We observed no significant differences in reaction times and P3 latency between the treatment groups.

CONCLUSION

Our data show electrophysiologic alterations in patients with breast cancer treated with high-dose chemotherapy 4 years after completion of treatment. The observed P3 reduction might be a result of suboptimal phasic cortical arousal and problems with the allocation of processing resources in these patients.

Adriamycin-induced, TNF-α-mediated central nervous system toxicity

The clinical effectiveness of adriamycin (ADR), a potent chemotherapeutic, is known to be limited by severe cardiotoxic side effects. However, the effect of ADR on brain tissue is not well understood. It is generally thought that ADR is not toxic to the brain because ADR does not pass the blood-brain barrier. The present study demonstrates that ADR autofluorescence was detected only in areas of the brain located outside the blood-brain barrier, but a strong tumor necrosis factor (TNF) alpha immunoreactivity was detected in the cortex and hippocampus of ADR-treated mice. Systemic injection of ADR led to a decline in brain mitochondrial respiration via complex I substrate shortly after ADR treatment (P < 0.05). Cytochrome c release, increased caspase 3 activity, and TUNEL-positive cell death all were suggestive of apoptosis in brain following systemic ADR treatment. The levels of the known pro-apoptotic proteins, p53 and Bax, were increased in brain mitochondria at 3 h following ADR treatment and declined by 48 h. In contrast, the anti-apoptotic protein, Bcl-xL, was increased later at 6 h post-ADR treatment and was sustained throughout 72 h. Furthermore, p53 migrated to mitochondria and interacted with Bcl-xL, supporting the hypothesis that mitochondria are targets of ADR-induced CNS injury. Neutralizing antibodies against circulating TNF completely abolished both the increased TNF in the brain and the observed mitochondrial injury in brain tissues. These results are consistent with the notion that TNF is an important mediator by which ADR induces central nervous system (CNS) injury. This study, the first to provide direct biochemical evidence of ADR toxicity to the brain, revealed novel mechanisms of ADR-induced CNS injury and suggests a potential therapeutic intervention against circulating TNF-induced CNS effects.

Electrophysiological correlates of information processing in breast-cancer patients treated with adjuvant chemotherapy

Cognitive deficits are found in a number of breast-cancer patients who have undergone adjuvant (Cyclophosphamide, Methotrexate, and 5-Fluorouracil (CMF)) chemotherapy, but the underlying mechanisms are still unclear. The objective of this study is to investigate information processing in these patients with concurrent registration of brain activity. Twenty-six breast-cancer patients treated with adjuvant CMF chemotherapy and a control group of 23 stage I breast-cancer patients not treated with chemotherapy were examined. Mean time since treatment for the CMF patients was 5.1 years after the last CMF course, and for the control patients 3.6 years after termination of radiotherapy. An information processing task was administered with concurrent EEG registration. Reaction times and the amplitudes and latencies of an Event Related Potential component (P3) in different task conditions related to input, central, and output processing of information were studied. Significant differences in latency and amplitude of the P3 component were found between the treatment groups with an earlier and reduced P3 in the chemotherapy group. Patients treated with chemotherapy had longer reaction times (although not significantly different) than the control group on all task conditions. Our data provide further evidence for long-term neurocognitive problems in breast-cancer patients treated with adjuvant (CMF) chemotherapy and offer new information regarding abnormalities in brain functioning in these patients.

Characteristics and correlates of cognitive functioning following bone marrow transplantation

Patients who undergo bone marrow transplantation (BMT) often report cognitive problems following treatment. This study used cognitive tests and a self-report measure of subjective cognitive complaints to determine (1) the rate of objective cognitive impairment in a sample of 65 BMT patients, and (2) the correspondence of patients' cognitive complaints to their actual cognitive performance. At 6 months following BMT, patients were assessed in seven cognitive domains--attention, verbal learning, verbal memory, visual memory, simple executive function, complex executive function, and psychomotor speed. Cognitive complaints were likewise assessed. In all, 51% had at least mild impairment (-1 standard deviation (s.d.) below published norms) in one or more cognitive domains, with 28% demonstrating moderate-to-severe impairment (-2 s.d.). Older patients and patients with lower IQ were more likely to score in the impaired range on objective cognitive tests, with males and the less educated showing trends toward scores in the impaired range. Younger patients made significantly more cognitive complaints. Total cognitive complaints were unrelated to average cognitive performance, and complaints in specific cognitive domains were largely unrelated to objective performance on corresponding domains. Findings suggest that patients who complain about their cognitive performance following BMT differ from those who experience actual deficits.

Cancer as a risk factor for long-term cognitive deficits and dementia

Previous studies have shown that cancer survivors frequently experience short-term cognitive deficits, but it is unknown how long these deficits last or whether they worsen over time. Using a co-twin control design, the cognitive function of 702 cancer survivors aged 65 years and older was compared with that of their cancer-free twins. Dementia rates were also compared in 486 of the twin pairs discordant for cancer. Cancer survivors overall, as well as individuals who had survived cancer for 5 or more years before cognitive testing, were more likely than their co-twins to have cognitive dysfunction (odds ratio [OR] = 2.10, 95% confidence interval [CI] = 1.36 to 3.24; P<.001; and OR = 2.71, 95% CI = 1.47 to 5.01; P<.001, respectively). Cancer survivors were also twice as likely to be diagnosed with dementia as their co-twins, but this odds ratio did not reach statistical significance (OR = 2.0, 95% CI = 0.86 to 4.67; P = .10). These results suggest that cancer patients are at increased risk for long-term cognitive dysfunction compared with individuals who have never had cancer, even after controlling for the influence of genetic factors and rearing environment.

The nature and severity of cognitive impairment associated with adjuvant chemotherapy in women with breast cancer: a meta-analysis of the current literature

OBJECTIVE

Several studies have identified that adjuvant chemotherapy for breast cancer is associated with cognitive impairment; however, the magnitude of this impairment is unclear. This study assessed the severity and nature of cognitive impairment associated with adjuvant chemotherapy by conducting a meta-analysis of the published literature to date.

METHOD

Six studies (five cross-sectional and one prospective) meeting the inclusion criteria provided a total of 208 breast cancer patients who had undergone adjuvant chemotherapy, 122 control participants and 122 effect sizes (Cohen's d) falling into six cognitive domains. First, the mean of all the effect sizes within each cognitive domain was calculated (separately for cross-sectional and prospective studies); second, a mean effect size was calculated for all of the effect sizes in each cross-sectional study; and third, regression analyses were conducted to determine any relationships between effect size for each study and four different variables.

RESULTS

For the cross-sectional studies, each of the cognitive domains assessed (besides attention) showed small to moderate effect sizes (-0.18 to -0.51). The effect sizes for each study were small to moderate (-0.07 to -0.50) and regression analysis detected a significant negative logarithmic relationship (R2 = .63) between study effect size and the time since last receiving chemotherapy. For the prospective study, effect sizes ranged from small to large (0.11-1.09) and indicated improvements in cognitive function from the beginning of chemotherapy treatment to 3 weeks and even 1 year following treatment.

CONCLUSION

This meta-analysis suggests that cognitive impairment occurs reliably in women who have undergone adjuvant chemotherapy for breast cancer but that the magnitude of this impairment depends on the type of design that was used (i.e., cross-sectional or prospective). Thus, more prospective studies are required before definite conclusions about the effects of adjuvant chemotherapy on cognition can be made.

[Acute central nervous symptoms in oncologic patients]

Oncologic patients may suffer from acute central nervous system disorders either related to the disease itself or to its therapy. These disorders may present as a disturbance of consciousness, as mental changes, as focal neurological signs, as epileptic seizures or as a combination of these. Symptoms may be caused by cerebral metastases, hemorrhage, ischemia or infectious complication, by metabolic changes or by treatment sequealae. This article will focus on clinical presentation, diagnostic workup and possible therapy or prophylaxis of these complications.

Neuropsychological dysfunction associated with cancer and cancer therapies: a conceptual review of an emerging target

Neuropsychological dysfunction associated with cancer and cancer treatment is a growing concern. Methodological limitations permeate the corpus of research in this area and have limited our understanding of the multifactorial nature of this process. The following review provides a summary of the current state of knowledge and highlights future directions.

Relationship of hemoglobin levels to fatigue and cognitive functioning among cancer patients receiving chemotherapy

The aim of this study was to examine the relationship of changes in hemoglobin levels to changes in fatigue and cognitive functioning in cancer patients undergoing chemotherapy treatment. Seventy-seven (77) patients completed a self-administered measure of fatigue and a battery of psychometrician-administered measures of cognitive performance before the start of chemotherapy and again before the start of the fourth treatment cycle. Hemoglobin levels were measured at corresponding timepoints. Findings partially supported the hypothesis that greater declines in hemoglobin over the course of repeated chemotherapy administrations would be accompanied by greater increases in fatigue and greater declines in cognitive performance over the same interval. Among the subset of 49 patients who demonstrated a decline in hemoglobin to a final value < or =12 g/dL, greater declines in hemoglobin were significantly (P<0.05) related to greater increases in fatigue duration and disruptiveness and more negative changes in performance on three cognitive tasks. These findings suggest that, in addition to previously reported relationships with fatigue, declines in hemoglobin levels during chemotherapy treatment are associated with adverse changes in cognitive functioning.

Cognitive impairment associated with chemotherapy for cancer: report of a workshop

Cognitive dysfunction may occur in some patients who receive chemotherapy. We provide a summary of an April 2003 workshop on this topic, that included medical oncologists, radiologists, clinical and experimental psychologists, and patient advocates. Current studies indicate that cognitive deficits are often subtle, although they are observed consistently in a proportion of patients, may be durable, and can be disabling. Deficits have been observed in a range of cognitive functions. Underlying mechanisms are unknown, although preliminary studies suggest there may be genetic predisposition and that cognitive impairment may be accompanied by changes in the brain detectable by neuroimaging. The following priorities were established for future research: (1) large-scale clinical studies that use both a longitudinal design and concurrent evaluation of patients with cancer who do not receive chemotherapy-such studies should address the probability and magnitude of cognitive deficits, factors that predict them, and underlying mechanisms; (2) exploration of discrepancies between subjective reports of cognitive dysfunction and the objective results of cognitive testing; (3) studies of cognitive function in patients receiving treatment for diseases other than breast cancer, and in both men and women, to address the hypothesis that underlying mechanisms relate to changes in serum levels of sex hormones and/or to chemotherapy-induced menopause; (4) development of interventions to alleviate these problems; and (5) development of animal models and the use of imaging techniques to address mechanisms that might cause cognitive impairment associated with chemotherapy.

What is the effect of systemic anticancer treatment on cognitive function?

Treatment regimens for solid tumours have been extensively investigated for their physical toxic effects, but far less is known about the potential impairment of cognitive function by anticancer treatment regimens. Here, we review published studies that examined cognitive function in adult patients receiving systemic therapy for solid tumours. Our review suggests that patients can experience cognitive changes related to their treatment. However, several studies had methodological limitations, such as use of a limited sample size, lack of baseline assessment, and lack of control for potential confounding factors. Better designed clinical trials are required so that the difficulties patients face in terms of reduced cognitive function as a result of anticancer treatment can be fully elucidated. These trials should have sufficient statistical power and, importantly, should also be prospective.

The impact of adjuvant therapy for breast cancer on cognitive function: current evidence and directions for research

Available evidence supports the hypothesis that adjuvant chemotherapy for breast cancer can produce cognitive deficits, and that these deficits may have a significant impact on patients' quality of life. Studies have generally compared the results of a variety of cognitive measures performed following treatment to standardized population-based norms or to cancer patients who received local therapy, rather than to the individual's baseline level of functioning. Several longitudinal studies are in progress or in the planning stages to better quantify and understand the incidence and impact of cognitive effects of adjuvant chemotherapy, and to identify possible susceptibility factors in subgroups. Although the neurocognitive changes appear to be subtle, there may be enough data to consider discussing the possibility of cognitive dysfunction as an adverse effect when assessing the risks and benefits of adjuvant chemotherapy. Likewise, as the aromatase inhibitors are increasingly given to larger numbers of women in the adjuvant setting, it will be important to understand the cognitive impact of estrogen deprivation. Finally, there is interest in examining supportive pharmacologic or behavioral measures that might prevent or decrease cognitive effects in this setting. Herein, the data on cognitive changes associated with chemotherapy for breast cancer, current and future research directions, as well as possible treatments are reviewed.

Toxicity of the high-dose chemotherapy CTC regimen (cyclophosphamide, thiotepa, carboplatin): the Netherlands Cancer Institute experience

High-dose chemotherapy (HD-CT) has a role in the potentially curative treatment of several tumours. The relative efficacies of the different regimens have not been studied in comparative trials, but it is clear that toxicities differ significantly between them. We analysed the immediate and long-term toxicity in the first 100 consecutive patients treated with the CTC regimen (cyclophosphamide 6000 mg m(-2), carboplatin 1600 mg m(-2) (or 20 mg ml(-1) min under the curve (AUC)) both as daily 1 h infusion, thiotepa 480 mg m(-2) as twice daily 30 min infusion, all divided over 4 consecutive days) followed by peripheral blood progenitor cell reinfusion (PBPC-Tx). Most patients had high-risk (n=86) or metastatic (n=4) breast cancer, or a germ cell tumour (n=8). Two patients (with a medulloblastoma and an aesthesioneuroblastoma, respectively) received CTC as off-protocol salvage regimen. The main toxicity was bone marrow suppression. Most patients had PBPC-Tx with granulocyte colony-stimulating factor (G-CSF), and the median time to neutrophil count 500 x 10(6) l(-1) and platelet count >20 x 10(9) l(-1) without transfusion independence was 10 (range 8-25) and 13 (8-60) days, respectively. The toxic death rate was 1%. Other frequent toxicities were neutropenic fever requiring antibiotics (n=65), central catheter-related infection (n=12) or a bleeding episode (n=48), mostly epistaxis (n=26). Reversible cardiac toxicity was seen in six patients and pulmonary events occurred in seven patients (infection (n=6), embolism (n=1)). Grade 3-4 gastrointestinal toxicity was frequent: nausea and vomiting 55%, diarrhoea 28% and mild liver toxicity (transaminase elevations) 9%. One patient pretreated with cisplatin had a kidney transplantation 8 years after HD-CT. Late complications included reversible radiation pneumonitis (n=12) and chronic heart failure (n=2). We found five second solid malignancies and two myelodysplasias. In conclusion, the CTC regimen is associated with a moderate, mainly reversible, toxicity. Future studies need to compare the efficacy and toxicity of the different HD-CT regimens.

Low neuropsychologic performance among adult cancer survivors treated with chemotherapy

Decline in neuropsychologic test performance following adjuvant chemotherapy for various types of cancer has gained much research attention over the past decade. From available data, about one fourth to one third of individuals undergoing systemic chemotherapy exhibit measurable decrements in performance of standard tests of cognitive function. Many cancer survivors report that cognitive problems interfere with function and compromise quality of life. However, these declines appear subtle and there are little available longitudinal data examining pre- to post-treatment cognitive change. Further, there is little available evidence identifying the causes of cognitive decline. This paper reviews current literature on low neuropsychologic performance following systemic chemotherapy and hypotheses on the causes of cognitive symptoms following chemotherapy. Future research directions, with emphasis on longitudinal research design as well as treatment implications, are discussed.

Adjuvant breast cancer treatment and cognitive function: current knowledge and research directions

Evidence is mounting that potentially curative systemic adjuvant therapy for early-stage breast cancer may result in cognitive impairment. Five published studies have investigated cognitive function in this setting, and the consistent results of all five studies suggest an adverse effect of adjuvant chemotherapy. These studies are reviewed with particular attention to their methodologic limitations. For example, all five studies used cross-sectional designs, none controlled for possible confounding hormonal factors, and three examined patients who had not received a uniform chemotherapy regimen. The potential roles of chemotherapy-induced menopause and of adjuvant hormonal therapy in cognitive impairment are also discussed. Priorities for future research include confirmation of an effect of adjuvant chemotherapy in a study with a longitudinal design, closer examination of the potential contribution of hormonal factors, and similar studies on the effect of adjuvant therapy on cognitive function in other cancer types. If an effect of systemic adjuvant therapy on cognitive function is confirmed, such an effect will have implications for informed consent. It may also result in incorporation of objective measures of cognition in clinical trials of adjuvant therapy and in the investigation of preventive interventions that might minimize the impact of cognitive dysfunction after cancer treatment.

Neurologic complications of radiation therapy

Injury to the central and peripheral nervous systems is an increasingly frequent consequence of standard radiation treatment protocols for tumors involving or adjacent to nervous system structures. Characteristic temporal, clinical, radiographic, and laboratory features distinguish a number of specific radiation injury syndromes, but meticulous and repeated evaluations over time are often required to establish a diagnosis. These syndromes vary with regard to prognosis and therapeutic options, and competing diagnoses with very different natural histories and therapies often mask or mimic the signs and symptoms of radiation-related nervous system injury. The ability to efficiently negotiate this complicated differential diagnostic landscape allows for early diagnosis of tumor recurrence or an alternative etiology, prompt institution of appropriate therapy, avoidance of unnecessary diagnostic studies, and confident prognostication for patients and families. Even after the diagnosis of a radiation-related complication is made, continued vigilance for additional sites or manifestations of radiation injury is mandatory. Meanwhile, further research into treatment, prevention, and the causes of individual susceptibility to radiation injury are essential.

Cognitive dysfunction and chemotherapy: neuropsychological findings in perspective

Currently, the interest in cognitive functioning following chemotherapy is rapidly expanding as is reflected in a growing number of published studies on this topic. Although most studies are indicative of cognitive deficits after chemotherapy, definite conclusions on the role of chemotherapy on cognitive function can often not be drawn due to methodological problems. On the basis of the studies on cognitive functioning after chemotherapy that are conducted in The Netherlands Cancer Institute, the current article describes a number of such methodological topics that obscure straightforward interpretation of neuropsychological findings in toxicity research. Measurement issues that diverge from usual assessment issues encountered in psychosocial oncology will be described, and factors that might play a role in the cause of cognitive impairment will be evaluated. Also, future developments necessary to gain more insight into the prevalence, the pattern, and the impact of cognitive problems following chemotherapy are discussed

Gamma knife radiosurgery in patients with advanced breast cancer undergoing bone marrow transplant

Object. Recent studies have suggested a high incidence of cognitive deficits in patients undergoing high-dose chemotherapy, which appears to be dose related. Whole-brain radiotherapy (WBRT) has previously been associated with cognitive impairment. The authors attempted to use gamma knife radiosurgery (GKS) to delay or avoid WBRT in patients with advanced breast cancer treated with high-dose chemotherapy and autologous bone marrow transplantation (HDC/ABMT) in whom brain metastases were diagnosed.

Methods. A retrospective review of our experience from 1996 to 2001 was performed to identify patients who underwent HDC/ABMT for advanced breast cancer and brain metastasis. They were able to conduct GKS as initial management to avoid or delay WBRT in 12 patients following HDC/ABMT. All patients were women. The median age was 48 years (range 30–58 years). The Karnofsky Performance Scale score was 70 (range 60–90). All lesions were treated with a median prescription dose of 17 Gy (range 15–18 Gy) prescribed to the 50% isodose.

Median survival was 11.5 months. Five patients (42%) had no evidence of central nervous system disease progression and no further treatment was given. Four patients were retreated with GKS and three of them eventually received WBRT as well. Two patients were treated with WBRT as the primary salvage therapy. The median time to retreatment with WBRT was 8 months after the initial GKS.

Conclusions. Gamma knife radiosurgery can be effectively used for the initial management of brain metastases to avoid or delay WBRT in patients treated previously with HDC, with acceptable survival and preserved cognitive function.

Breast cancer chemotherapy-related cognitive dysfunction

Cognitive side effects of systemic chemotherapy have become an increasing concern among breast cancer survivors, their families, and health care professionals. A growing body of research supports the hypothesis that chemotherapy can produce long-term cognitive changes in at least a subgroup of cancer survivors. We review evidence implicating systemic chemotherapy as the cause of cognitive changes; describe the limitations due to lack of longitudinal studies and gaps in knowledge (ie, no clear mechanism by which chemotherapy can produce cognitive changes has been proposed); discuss possible factors like age, intelligence quotient/education, and psychological, genetic, and hormonal factors that might increase risk for chemotherapy-induced cognitive changes; and outline future directions for research. Such future research includes large-scale, longitudinal studies of pretreatment neuropsychological assessments, use of imaging techniques and the development of animal models to study the mechanisms of chemotherapy-induced changes in cognitive functioning, and the development of interventions to prevent or reduce the negative cognitive effects of chemotherapy

Memory for context is impaired by a post context exposure injection of interleukin-1 beta into dorsal hippocampus

Prior research has revealed that treatments that elevate the level of the pro-inflammatory cytokine IL-1beta in the brain, if given after training, impair contextual but not auditory-cue fear conditioning. The present experiments add to these finding by showing that, (a) IL-1beta exerts its effect on contextual fear conditioning by impairing consolidation processes that support the storage of the memory representation of the context; (b) the dorsal hippocampus is a critical site for the effect of IL-1beta; (c) the effect of IL-1beta cannot be attributed to its effect on glucocorticoid levels; and (d) IL-1beta injected into dorsal hippocampus either, immediately, 3, or 24 h, but not 48 h, after training produces this impairment. At this time the mechanisms responsible for this impairment are not understood, but may involve late-phase protein synthesis processes associated with LTP, because later consolidation processes are being disrupted.