Purpose: Evidence is mixed regarding long-term cognitive deficits in patients treated with chemotherapy. Previous meta-analyses have not focused specifically on the postchemotherapy period and have not incorporated several recent studies. The goal of the current study was to conduct a meta-analysis of cognitive functioning in breast cancer survivors who were treated with chemotherapy ≥ 6 months previously.
Methods: A search of PubMed, PsycInfo, Cumulative Index to Nursing and Allied Health Literature, and Cochrane Library yielded 2,751 abstracts, which were independently evaluated by pairs of raters. Meta-analysis was conducted on 17 studies of 807 patients previously treated with standard-dose chemotherapy for breast cancer. Neuropsychological tests were categorized according to eight cognitive domains: attention, executive functioning, information processing, motor speed, verbal ability, verbal memory, visual memory, and visuospatial ability.
Results: Deficits in cognitive functioning were observed in patients treated with chemotherapy relative to controls or prechemotherapy baseline in the domains of verbal ability (g = -0.19; P < .01) and visuospatial ability (g = -0.27; P < .01). Patients treated with chemotherapy performed worse than noncancer controls in verbal ability and worse than patients treated without chemotherapy in visuospatial ability (both P < .01). Age, education, time since treatment, and endocrine therapy did not moderate observed cognitive deficits in verbal ability or visuospatial ability (all P ≥ .51).
Conclusion: Results indicate that, on average, observed cognitive deficits in patients with breast cancer previously treated with chemotherapy are small in magnitude and limited to the domains of verbal ability and visuospatial ability. This information can be used to inform interventions to educate patients with breast cancer regarding the long-term impact of chemotherapy on cognitive functioning.