Background
Findings from longitudinal studies can provide more conclusive evidence as to the impact of chemotherapy on cognitive functioning.
Objectives
This study aimed to (a) synthesize the evidence from longitudinal studies of the neuropsychological effects associated with chemotherapy in breast cancer patients, (b) identify associated factors, and (c) evaluate methodological issues.
Methods
Data were extracted from PubMed, EMBASE, CINAHL, PsycINFO, and the Cochrane Library. Inclusion criteria included the original study with the breast cancer sample, validated measure, and at least 1 baseline data point before and after chemotherapy began. Data accrued for sample characteristics, data-collection time points, statistical methods for longitudinal data analysis, outcome measures, and major findings (eg, longitudinal changes in cognitive function).
Results
We selected 42 articles for this review. The sample sizes ranged from 20 to 610, and most recruited were younger than 70 years. We found a trend across studies—statistically significant objective cognitive function deteriorations in severity and prevalence after initiating chemotherapy compared with a control group or relative to their baseline observations. A subsample, as high as 65%, experienced marked declines in cognitive function after initiating chemotherapy. The memory domain was most affected. The consistently associated factors were education, IQ, and regimen. Major methodological concerns were the measurement—the wide range of neuropsychological tests and a test’s unclear domains.
Conclusion
Chemotherapy affects objective cognitive function in some subsets. The highest-impact time point, mechanisms, and clinical significance of chemotherapy-associated cognitive impairment need additional evidence.
Implication for Practice
Clinicians must assess and manage cognitive impairment during and after chemotherapy.
