Elsevier

Cancer Treatment Reviews

Volume 38, Issue 7, November 2012, Pages 926-934
Cancer Treatment Reviews

Complications of Treatment
Objective and subjective cognitive impairment following chemotherapy for cancer: A systematic review

https://doi.org/10.1016/j.ctrv.2012.05.002Get rights and content

Summary

Evidence suggests that some cancer survivors experience cognitive difficulties following chemotherapy. However, perceived or subjective cognitive impairment is more frequently reported than prevalence revealed by objective assessments. The aim of this review was to examine the relationship between subjective and objective measures of cognitive impairment following treatment for cancer and to determine the number of studies that found a significant relationship between these measures of cognition. A comprehensive search for articles, published between 1980 and 2012, comparing subjective and objective cognition in cancer patients treated with chemotherapy was conducted. Of 818 potentially relevant articles, 23 studies met the inclusion criteria for the current review and one article was sourced from reference lists of included studies. Only eight of 24 included studies found a significant relationship between objective and subjective measures of cognitive performance. These studies were more likely to involve breast cancer patients and to assess the relationship between memory and perceived cognitive impairment. The failure to consistently find an association between subjective and objective measures of cognition could be explained by variations in assessment methods or the definition of impairment. Alternatively, objective and perceived cognitive impairment may be unrelated because perceived impairment may be an indicator of psychological distress rather than cognitive impairment. Despite these discrepancies, patients’ perceptions of impairment are important due to its significant impact on quality of life. Further research is required to explore whether objective measures of everyday functioning better predict the impact of chemotherapy related cognitive impairment on daily functioning.

Section snippets

Objective Measures of Cognitive Impairment Following Chemotherapy for Cancer

Cognitive function following chemotherapy, measured objectively through neuropsychological tests, has received considerable attention.1, 4, 5, 6Research using neuropsychological tests indicates that chemotherapy affects many domains of cognition, including executive function, processing speed, attention/concentration, and verbal and visual memory.1, 7, 8 Anderson-Hanley et al.’s meta-analysis of the results of 30 studies suggests that the domains of memory and executive function are

Subjective Measures of Cognitive Impairment Following Chemotherapy for Cancer

Perceived cognitive impairment, measured using self-report questionnaires or interviews, is arguably as important as objective impairment because it assesses the impact of cognitive impairment on individuals’ lives and daily functioning.13 When interviewed immediately following chemotherapy and up to 12 months after treatment completion, many patients with cancer report changes in their memory and attention, and describe particular difficulties with multi-tasking and making decisions in daily

Search Strategy and Selection Criteria

The following MEDLINE and PubMed search was conducted on April 5, 2012: cancer AND chemotherapy AND (cognitive OR cognition) AND (assessment OR objective OR neuropsychological OR neuropsychology OR subjective OR self-report). Other relevant articles were sourced from the reference lists of included papers. The search was limited to human studies, papers published in English, and studies published after 1980, when studies began to report prevalence of both perceived cognitive impairment and

Studies Comparing Perceived (Subjective) Impairment and Neuropsychological (Objective) Assessments of Cognition

It is well established that chemotherapy patients often perceive deficits in their cognitive functioning and that such perceptions are related to quality of life, anxiety, depression and fatigue. However, studies that assess the relationship between objective neuropsychological test performance and self-reported cognitive difficulties have found small or non-significant associations.1, 2, 12, 19 Table 1 summarises the studies that have examined both self-reported cognitive impairment and more

Discussion

Impaired cognitive function following chemotherapy treatment for cancer has been well documented and it is estimated that some degree of difficulty is experienced by 15% to 50% of patients with solid tumours. Perceived impairment is more common than objectively confirmed impairment and, within patient samples, there is often little or no association between the two. This was consistent with the current review, which only found an association in one third of included studies. Studies were more

Summary and Recommendations for Future Research

To the extent that some studies report an association between subjective experience and objective measures, whereas others do not, it is possible that the association is only evident where both can be linked to objective reports of difficulties with everyday problems. Unfortunately, these are rarely measured notwithstanding the existence of scales like the Everyday Problems Test (EPT)45. Future research should examine the extent to which concordance between objective neuropsychological measures

Conflict of Interest Statement

There are no conflicts of interest to declare for any of the authors.

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