Prevalence of cognitive impairment following chemotherapy treatment for breast cancer: a systematic review and meta-analysis

Abstract

Breast cancer survival rates have markedly improved. Consequently, survivorship issues have received increased attention. One common sequel of treatment is chemotherapy-induced cognitive impairment (CICI). CICI causes a range of impairments that can have a significant negative impact on quality of life. Knowledge of the prevalence of this condition is required to inform survivorship plans, and ensure adequate resource allocation and support is available for sufferers, hence a systematic review of prevalence data was performed. Medline, Scopus, CINAHL and PSYCHInfo were searched for eligible studies which included prevalence data on CICI, as ascertained though the use of self-report, or neuropsychological tests. Methodological quality of included studies was assessed. Findings were synthesised narratively, with meta-analyses being used to calculate pooled prevalence when impairment was assessed by neuropsychological tests. The review included 52 studies. Time-points considered ranged from the chemotherapy treatment period to greater than 10 years after treatment cessation. Summary prevalence figures (across time-points) using self-report, short cognitive screening tools and neuropsychological test batteries were 44%, 16% and 21-34% respectively (very low GRADE evidence). Synthesised findings demonstrate that 1 in 3 breast cancer survivors may have clinically significant cognitive impairment. Prevalence is higher when self-report based on patient experience is considered. This review highlights a number of study design issues that may have contributed to the low certainty rating of the evidence. Future studies should take a more consistent approach to the criteria used to assess impairment. Larger studies are urgently needed.

Figure 1

The PRISMA flow diagram for the systematic review detailing the databases searched, the number of abstracts screened and the full texts retrieved.

Figure 2

Risk of bias graph: review authors' judgements about each methodological quality item presented as percentages across all included studies. Study number = 52.

Figure 3

Boxplot of prevalence reported for cognitive impairment, via self-report methods, across the time-points included in the review (data from 12 studies in Tables 1, 3 studies were excluded due to mixed or unclear timing of assessment^,,).

Figure 4

Boxplot of prevalence reported for cognitive impairment, via short cognitive screening methods, across the time-points included in the review. Ng et al. 2018 was excluded from the calculation since a range was reported, and only considering moderate-severe classification of impairment from and.

Figure 5

Forest plots of prevalence reported in studies utilising neuropsychological tests to diagnose cognitive impairment following chemotherapy treatment for breast cancer. (A) Cognitive assessment undertaken during chemotherapy treatment (T1), (B) Cognitive assessment undertaken just after cessation of chemotherapy treatment (T2), (C) Cognitive assessment undertaken 6 months after cessation of chemotherapy treatment (T3), (D) Cognitive assessment undertaken 1 year after cessation of chemotherapy treatment (T4), (E) Cognitive assessment undertaken 2–3 years after cessation of chemotherapy treatment (T5).

Figure 6

Prevalence reported for cognitive impairment, via neuropsychological test methods, across the time-points included in the review. Data represent pooled prevalence estimates derived from meta-analysis, with 95% CIs. ∞—values are not pooled figures but represent individual values from one study.

Figure 7

Forest plots of prevalence sub-grouped by stringency of cognitive assessment. (A) Cognitive assessment undertaken just after cessation of chemotherapy treatment (T2), (B) Cognitive assessment undertaken 6 months after cessation of chemotherapy treatment (T3).