The effect of modafinil on cognitive function in breast cancer survivors

Long-term toxic effects of adjuvant chemotherapy in breast cancer

Breast cancer is the most common malignant tumor affecting women. Adjuvant systemic therapies have been shown to have a significant impact on reducing the risk for breast cancer recurrence and overall mortality. Chemotherapy remains an important and frequently used treatment option in the adjuvant setting, and the associated short-term adverse events are very well described. However, there is insufficient information regarding the long-term sequelae of most chemotherapeutic agents. In this review, we describe different potential long-term adverse events associated with adjuvant chemotherapy in breast cancer, with a particular focus on long-term cardiac toxicity, secondary leukemia, cognitive function, and neurotoxicity. In addition, we discuss the effect of adjuvant chemotherapy on fertility and sexual function of young breast cancer patients. These adverse events are frequently overshadowed by the well-demonstrated clinical efficacy and/or reassuring short-term safety profiles of the different chemotherapy regimens commonly used today. We believe that a proper understanding and appreciation of these adverse events will enable us to refine our strategies for managing breast cancer. The fact that adjuvant chemotherapy is often given to patients who might not really need it urges us to consider the whole spectrum of chemotherapy risks versus benefits to maximize benefit without compromising quality of life.

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.

Interventions to Alleviate Symptoms Related to Breast Cancer Treatments and Areas of Needed Research

Treatments for breast cancer produce a host of side effects, which can become debilitating. Some cancer treatment-related side effects occur in up to 90% of patients during treatment and can persist for months or years after treatment has ended. As the number of breast cancer survivors steadily increases, the need for cancer control intervention research to alleviate side effects also grows. This review provides a general overview of recent clinical research studies of selected topics in the areas of symptom management for breast cancer with a focus on cognitive difficulties, fatigue, cardiotoxicity, bone loss, insomnia, and cancer pain. We review both pharmacological and behavioral intervention clinical research studies, conducted with breast cancer patients and survivors. Additionally, clinical perspectives on symptom management and recommendations for areas of needed research are provided.

Either called "chemobrain" or "chemofog," the long-term chemotherapy-induced cognitive decline in cancer survivors is real

CONTEXT

In recent years, there is growing evidence in the medical literature to support an association between administration of commonly used chemotherapeutic agents and an increased risk for cognitive impairment.

OBJECTIVES

We herein critically summarize data relating to the pathophysiological mechanisms by which chemotherapy may induce cognitive impairment in patients surviving from solid tumors. The clinical and epidemiological characteristics and the proposed management strategies to counter chemotherapy-induced cognitive impairment (CICI) also are presented.

METHODS

References for this review were identified by searches of PubMed from 1995 until December 2009 with related terms.

RESULTS

Both the pathogenetic mechanisms and the overall clinical nature of CICI remain vaguely defined. Findings indicate that CICI is a relatively common event that, in most of the cases, remains underdiagnosed, thereby adversely affecting the quality of life of patients with cancer. Effective pharmacological interventions toward the symptomatic or prophylactic management of CICI also are lacking.

CONCLUSION

Either called "chemobrain" or "chemofog," the long-term CICI in cancer survivors is real. The need for multidisciplinary care interventions toward a timely diagnosis and management of CICI is clearly warranted.

Neurological complications of systemic cancer

Neurological complications of systemic cancer-those arising outside the nervous system-can be distressing, disabling, and sometimes fatal. Diagnosis is often difficult because different neurological disorders may present with similar signs and symptoms. Furthermore, comorbid neurological illnesses, common in elderly patients with cancer, can complicate diagnosis. Early diagnosis and aggressive treatment can improve neurological symptoms and can substantially enhance a patient's quality of life. We approach the problem of neurological complications of systemic cancer as would a neurologist: first by identifying the anatomical area or areas that are affected (ie, brain, spinal cord, peripheral nerve), then by evaluating the diagnostic approach, considering the symptoms and signs and including appropriate laboratory tests, and finally, by recommending treatment. We focus on disorders that are difficult to diagnose, need neurological consultation, and for which effective treatments exist.

Breast cancer treatment and cognitive function: the current state of evidence, underlying mechanisms and potential treatments

Within the last decade, several studies have investigated whether adjuvant treatment of breast cancer affects cognitive function. A number of prospective studies have demonstrated inconsistent results regarding whether chemotherapy affects cognitive function. Approximately half of the studies demonstrated subtle cognitive decline in a wide range of domains among some breast cancer patients following chemotherapy, and half did not. Concomitant changes in brain structure and function have been identified in neuroimaging and neurophysiologic studies. Estrogenic therapy has been specifically associated with deterioration in verbal memory and processing speed. However, evidence is mostly based on smaller studies with cross-sectional data. Breast cancer patients who underwent both chemotherapy and estrogenic therapy showed the most deterioration and the most persistent decline in cognitive function. Since cognitive impairment is subtle, if evident at all, discrepant findings are due to hormonal, physiological, psychological or temporal confounding variables and differences in study design. Neuropsychological training has been demonstrated to improve cognitive dysfunction experienced by breast cancer patients after chemotherapy. Future research may examine the unique impact of endocrine therapy on cognitive function with prospective, controlled trials, as well as the role of further confounding variables (e.g., menopausal status, cytokine deregulation, cortisol and concurrent medication).

Psychostimulant-like discriminative stimulus and locomotor sensitization properties of the wake-promoting agent modafinil in rodents

The present studies assessed the potential abuse liability and likely mechanism(s) of action of the wake-promoting agent modafinil.

METHODS

Experiments assessed the locomotor sensitization (LS) and discriminative stimulus (DS) properties of modafinil in mouse and rat, respectively. Comparative data were generated with a range of psychostimulants and monoamine reuptake inhibitors.

RESULTS

Repeated administration of d-amphetamine and cocaine, psychostimulants with high abuse liability, resulted in the induction and expression of LS in mice. Bupropion and caffeine, two psychostimulants not abused in humans, were not associated with LS. GBR12909 induced LS during repeated exposure, but there was no evidence of expression of LS after acute challenge following withdrawal. In contrast, repeated administration of modafinil resulted in the expression, but not induction, of LS. d-amphetamine, but not the mu-opioid agonist morphine or the nAChR agonist nicotine, fully substituted for the cocaine DS in rats. The selective dopamine transporter (DAT) inhibitor GBR12909 fully substituted, the preferential norepinephrine transporter (NET) inhibitor desipramine partially substituted, and the selective serotonin reuptake inhibitor citalopram failed to substitute for cocaine. Modafinil fully substituted for cocaine, similar to the mixed DAT/NET inhibitor bupropion.

CONCLUSIONS

Two preclinical assays indicated potential abuse liability of modafinil; drug discrimination studies suggest DAT blockade by modafinil is a likely mechanism of action in vivo.