Neuropsychological Effects of Chemotherapy: Systematic Review of Longitudinal Studies on Objective Cognitive Impairment in Breast Cancer Patients.

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.