As the population of cancer survivors has grown into the millions, there has been increasing emphasis on understanding how the late effects of treatment affect survivors’ ability to return to work/school, their capacity to function and live independently, and their overall quality of life. This review focuses on cognitive change associated with cancer and cancer treatments. Research in this area has progressed from a pharmacotoxicology perspective to a view of the cognitive change as a complex interaction of aspects of the treatment, vulnerability factors that increase risk for posttreatment cognitive decline, cancer biology, and the biology of aging. Methodological advances include the development of (a) measurement approaches that assess more fine-grained subcomponents of cognition based on cognitive neuroscience and (b) advanced statistical approaches. Conceptual issues that arise from this multidimensional perspective are described in relation to future directions, understanding of mechanisms, and development of innovative interventions.

We evaluated deficit accumulation and how deficits affected cognition and physical activity among breast cancer survivors and non-cancer controls. Newly diagnosed nonmetastatic survivors (n = 353) and matched non-cancer controls (n = 355) ages 60-98 years without neurological impairments were assessed presystemic therapy (or at enrollment for controls) from August 2010 to December 2016 and followed for 36 months. Scores on a 42-item index were analyzed in growth-mixture models to determine deficit accumulation trajectories separately and combined for survivors and controls. Multilevel models tested associations between trajectory and cognition (FACT-Cog and neuropsychological tests) and physical activity (IPAQ-SF) for survivors and controls. Deficit accumulation scores were in the robust range, but survivors had higher scores (95% confidence intervals [CI]) than controls at 36 months (0.18, 95% CI = 0.16 to 0.19, vs 0.16, 95% CI = 0.14 to 0.17; P = .001), and averages included diverse deficit trajectories. Survivors who were robust but became frailer (8.8%) had similar baseline characteristics to those remaining robust (76.2%) but experienced a 9.6-point decline self-reported cognition (decline of 9.6 vs 3.2 points; P = .04) and a 769 MET minutes per week decline in physical activity (P < .001). Survivors who started and remained prefrail (15.0%) had self-reported and objective cognitive problems. At baseline, frail controls (9.5%) differed from robust controls (83.7%) on deficits and self-reported cognition (P < .001). Within combined trajectories, frail survivors had more sleep disturbances than frail controls (48.6% [SD = 17.4%] vs 25.0% [SD = 8.2%]; P = .05). Most survivors and controls remained robust, and there were similar proportions on a frail trajectory. However, there were differences in deficit patterns between survivors and controls. Survivor deficit accumulation trajectory was associated with patient-reported outcomes. Additional research is needed to understand how breast cancer and its treatments affect deficit accumulation.

Cognitive decline is among the most feared treatment-related outcomes of older adults with cancer. The majority of older patients with breast cancer self-report cognitive problems during and after chemotherapy. Prior neuroimaging research has been performed mostly in younger patients with cancer. The purpose of this study was to evaluate longitudinal changes in brain volumes and cognition in older women with breast cancer receiving adjuvant chemotherapy. Women aged ≥ 60 years with stage I–III breast cancer receiving adjuvant chemotherapy and age-matched and sex-matched healthy controls were enrolled. All participants underwent neuropsychological testing with the US National Institutes of Health (NIH) Toolbox for Cognition and brain magnetic resonance imaging (MRI) prior to chemotherapy, and again around one month after the last infusion of chemotherapy. Brain volumes were measured using Neuroreader™ software. Longitudinal changes in brain volumes and neuropsychological scores were analyzed utilizing linear mixed models. A total of 16 patients with breast cancer (mean age 67.0, SD 5.39 years) and 14 age-matched and sex-matched healthy controls (mean age 67.8, SD 5.24 years) were included: 7 patients received docetaxel and cyclophosphamide (TC) and 9 received chemotherapy regimens other than TC (non-TC). There were no significant differences in segmented brain volumes between the healthy control group and the chemotherapy group pre-chemotherapy (p > 0.05). Exploratory hypothesis generating analyses focusing on the effect of the chemotherapy regimen demonstrated that the TC group had greater volume reduction in the temporal lobe (change = − 0.26) compared to the non-TC group (change = 0.04, p for interaction = 0.02) and healthy controls (change = 0.08, p for interaction = 0.004). Similarly, the TC group had a decrease in oral reading recognition scores (change = − 6.94) compared to the non-TC group (change = − 1.21, p for interaction = 0.07) and healthy controls (change = 0.09, p for interaction = 0.02). There were no significant differences in segmented brain volumes between the healthy control group and the chemotherapy group; however, exploratory analyses demonstrated a reduction in both temporal lobe volume and oral reading recognition scores among patients on the TC regimen. These results suggest that different chemotherapy regimens may have differential effects on brain volume and cognition. Future, larger studies focusing on older adults with cancer on different treatment regimens are needed to confirm these findings. ClinicalTrials.gov, NCT01992432 . Registered on 25 November 2013. Retrospectively registered.