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

Long-lasting suppression of hippocampal cell proliferation and impaired cognitive performance by methotrexate in the rat

Methotrexate (MTX) is a cytostatic agent widely used in combination with other agents as adjuvant chemotherapy for breast cancer and is associated with cognitive impairment as a long-term side effect in some cancer patients. This paper aimed to identify a neurobiological mechanism possibly responsible for this cognitive impairment using an animal model. The first study explored the hypothesis that MTX reduces neuronal cell proliferation. Adose-dependent long-lasting decrease in hippocampal cell proliferation was shown with Ki-67 immunocytochemistry, following a single intravenous injection of MTX (37.5–300 mg/kg). Animals treated with MTX also showed a dose-dependent transient decrease in body weight gain. In the second study, the effect of MTX (250 mg/kg) on two spatial learning tasks was examined. Animals treated with MTX learned the Morris water maze task adequately; however, these animals showed a longer latency time to cross the platform location in the probe trial, reflecting an impairment of spatial memory function. In the novel object recognition task, animals treated with MTX failed to distinguish a novel object from a familiar one, indicating a decrease in the comparator function of the hippocampus. Our studies indicated that, in the rat, MTX has a dose-dependent negative effect on hippocampal cell proliferation, and on cognitive behavior. These findings suggest that adverse effects of certain cytotoxic agents on hippocampal cell proliferation may have a potential contributory role in cognitive impairment observed in humans after chemotherapy.

Inhibition of hippocampal cell proliferation by methotrexate in rats is not potentiated by the presence of a tumor

Methotrexate is a widely used cytostatic in chemotherapy cocktails for the treatment of cancer but is associated with cognitive impairment. Previous animal studies indicated that methorexate decreases hippocampal cell proliferation, which might contribute to the observed cognitive impairment. However, clinical studies have shown that cognitive impairment can also be noticed in some cancer patients before any systemic treatment is initiated. We aim in the present study to discern whether hippocampal cell proliferation is negatively affected by tumor growth and if the presence of a tumor amplifies the effects of methotrexate. Buffalo rats were subcutaneously injected with PBS or Morris Hepatoma 7777 cells to induce a tumor. Two weeks after this injection the animals received an intraperitoneal injection of methotrexate or saline. Three weeks later hippocampal cell proliferation was quantified using immunohistochemical staining. Treatment with Morris Hepatoma 7777 cells decreased the number of proliferating cells as compared to control animals. An overall tumor effect was absent mainly because methotrexate treatment significantly decreased cell proliferation with no differences between animals with or without a tumor. Neither methotrexate nor the tumor induced pica behavior. These findings indicate that although the presence of a tumor reduces hippocampal cell proliferation it does not affect the negative effect of methotrexate on this plasticity marker. Since sickness behavior is not induced by methotrexate or tumor presence it does not play a role in the development of cognitive deficits. This study further indicates that the effects of methotrexate on brain and behavior can be studied in healthy animals.

Methotrexate decreases hippocampal cell proliferation and induces memory deficits in rats

Methotrexate (MTX) is a cytostatic agent used in adjuvant chemotherapy for treatment of breast cancer and is associated with cognitive impairment in a subgroup of patients. The aim of this paper is to test whether MTX can rapidly affect various brain structures resulting in decreased hippocampal cell proliferation and white matter damage. We also studied whether cell death occurs in the hippocampus following MTX. All these processes may contribute to the memory deficits reported in patients. The first study explored the effect of an intravenously injected high-dose MTX (250 mg/kg) on hippocampal cell proliferation, white matter, and cell death. Proliferation was not significantly decreased 1 day after administration of MTX, although a high individual variation was seen. However, 7 days after MTX treatment hippocampal cell proliferation was significantly lower compared to control animals. White matter density was decreased in the lateral corpus callosum of animals treated with MTX, 1 day, 1 week, and 3 weeks after treatment. MTX did not induce hippocampal cell death at any of the time intervals after treatment. The second study examined the effect of MTX on memory by subjecting animals to a learning task directly followed with MTX treatment. In both learning tasks, memory was impaired in treated animals. In the Morris water maze, animals treated with MTX spent significantly less time in the correct quadrant compared to control animals during the probe trial which was performed 1 week after training and treatment. In contextual fear conditioning, animals treated with MTX showed significantly less freezing behavior compared to control animals, 4 weeks after training and treatment. These studies suggest that the negative effect of MTX on hippocampal cell proliferation and white matter density may be part of the mechanisms underlying the cognitive impairment observed as side effect after cytotoxic treatment in humans.

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

Methotrexate reduces hippocampal blood vessel density and activates microglia in rats but does not elevate central cytokine release

Methotrexate is a cytostatic drug applied in adjuvant chemotherapy and associated with cognitive impairment in part of the cancer patients. In this paper we studied in rats whether a reduction in blood supply to the brain or neuroinflammation are possible mediators of this cognitive dysfunctionality. Methotrexate reduced hippocampal blood vessel density 1 week and 3 weeks after treatment as measured immunohistochemically with an endothelial barrier antigen. Since reduced brain vascularization may relate to lowered central glucose metabolism [18F]FDG PET was performed. Methotrexate reduced tracer uptake in the hippocampal region 1 week after treatment, which was not seen 3 weeks after treatment. Neuroinflammatory processes were explored via a number of methods: a microglia immunohistochemical marker was applied to hippocampal sections, [11C]PK11195 PET was performed, and cytokine levels in plasma and homogenized hippocampal tissue were measured. Methotrexate activated microglia in the hippocampus 1 week and 3 weeks after treatment. PET analysis, however, did not show an increase in hippocampal tracer uptake and the multiplex analysis of various cytokines showed that hippocampal cytokine levels were not increased after methotrexate administration. Methotrexate did reduce plasma cytokine levels indicating a suppression of peripheral immune functioning. Methotrexate reduces hippocampal blood vessel density, indicative of a reduced brain glucose metabolism, which may contribute to the cognitive impairment following methotrexate administration. Although methotrexate activates microglia activation in the hippocampus, no effects were seen in [11C]PK11195 tracer uptake or hippocampal cytokine levels. This suggests that the microglial activation in this study is not a marker for neuroinflammation.

Constructive Technology Assessment (CTA) as a tool in coverage with evidence\ud development: the case of the 70-gene prognosis signature for breast cancer diagnostics

Objectives:\ud Constructive Technology Assessment (CTA) is a means to guide early implementation of new developments in society, and can be used as an evaluation tool for Coverage with Evidence Development (CED). We used CTA for the introduction of a new diagnostic test in the Netherlands, the 70-gene prognosis signature (MammaPrint®) for node-negative breast cancer patients.\ud \ud Methods:\ud Studied aspects were (organizational) efficiency, patient-centeredness and diffusion scenarios. Pre-post structured surveys were conducted in fifteen community hospitals concerning changes in logistics and teamwork as a consequence of the introduction of the 70-gene signature. Patient-centeredness was measured by questionnaires and interviews regarding knowledge and psychological impact of the test. Diffusion scenarios, which are commonly applied in industry to anticipate on future development and diffusion of their products, have been applied in this study.\ud \ud Results:\ud Median implementation-time of the 70-gene signature was 1.2 months. Most changes were seen in pathology processes and adjuvant treatment decisions. Physicians valued the addition of the 70-gene signature information as beneficial for patient management. Patient-centeredness (n = 77, response 78 percent): patients receiving a concordant high-risk and discordant clinical low/high risk-signature showed significantly more negative emotions with respect to receiving both test-results compared with concordant low-risk and discordant clinical high/low risk-signature patients. The first scenario was written in 2004 before the introduction of the 70-gene signature and identified hypothetical developments that could influence diffusion; especially the “what-if” deviation describing a discussion on validity among physicians proved to be realistic.\ud \ud Conclusions:\ud Differences in speed of implementation and influenced treatment decisions were seen. Impact on patients seems especially related to discordance and its successive communication. In the future, scenario drafting will lead to input for model-based cost-effectiveness analysis. Finally, CTA can be useful as a tool to guide CED by adding monitoring and anticipation on possible developments during early implementation, to the assessment of promising new technologies

Constructive Technology Assessment (CTA) as a tool in coverage with evidence development: the case of the 70-gene prognosis signature for breast cancer diagnostics

Objectives: Constructive Technology Assessment (CTA) is a means to guide early implementation of new developments in society, and can be used as an evaluation tool for Coverage with Evidence Development (CED). We used CTA for the introduction of a new diagnostic test in the Netherlands, the 70-gene prognosis signature (MammaPrint®) for node-negative breast cancer patients. Methods: Studied aspects were (organizational) efficiency, patient-centeredness and diffusion scenarios. Pre-post structured surveys were conducted in fifteen community hospitals concerning changes in logistics and teamwork as a consequence of the introduction of the 70-gene signature. Patient-centeredness was measured by questionnaires and interviews regarding knowledge and psychological impact of the test. Diffusion scenarios, which are commonly applied in industry to anticipate on future development and diffusion of their products, have been applied in this study. Results: Median implementation-time of the 70-gene signature was 1.2 months. Most changes were seen in pathology processes and adjuvant treatment decisions. Physicians valued the addition of the 70-gene signature information as beneficial for patient management. Patient-centeredness (n = 77, response 78 percent): patients receiving a concordant high-risk and discordant clinical low/high risk-signature showed significantly more negative emotions with respect to receiving both test-results compared with concordant low-risk and discordant clinical high/low risk-signature patients. The first scenario was written in 2004 before the introduction of the 70-gene signature and identified hypothetical developments that could influence diffusion; especially the “what-if” deviation describing a discussion on validity among physicians proved to be realistic. Conclusions: Differences in speed of implementation and influenced treatment decisions were seen. Impact on patients seems especially related to discordance and its successive communication. In the future, scenario drafting will lead to input for model-based cost-effectiveness analysis. Finally, CTA can be useful as a tool to guide CED by adding monitoring and anticipation on possible developments during early implementation, to the assessment of promising new technologies