Comparison of Functional and Cognitive Capacity Among Cancer Survivors and Cancer-free Individuals in an Older US population

Background The global population is aging rapidly, and cancer is one of the major health concerns of an aging population. Older cancer survivors can be challenged by the toxicities associated with cancer and its treatment in addition to the normal declines in functional and cognitive capacities due to aging. However, we only have limited data on whether older cancer survivors have worse functional and cognitive capacity profiles than their cancer-free counterparts. Method For this study, 7,459 participants from Health and Retirement Study (HRS) and completed functional capacity questionnaire between Feb 2016 to April 2018 were included, among which 1,238 are cancer survivors, and the rest are cancer-free. Answers from biennial HRS questionnaires were used for exposure and outcome ascertainment. Poisson regression models with robust variance were used to estimate the risk ratio (RR) for the association between cancer history and prevalence of functional and cognitive limitation. Stratified analysis by race/ethnicity was performed to explore potential race/ethnic group differences. Sensitivity analyses excluding demented participants were performed to evaluate the reliability of the primary analyses. Results A significant positive association was observed between cancer history and any disability in basic ADLs (adjusted Risk Ratio = 1.09, 95% CI (1.01, 1.18). A significant positive association was observed between cancer history and any disability in IADLs (adjusted Risk Ratio = 1.11 (1.02, 1.22). Cognitive capacity did not differ significantly between cancer survivors and cancer-free participants. Low educational level, depressive symptoms within 12-month, and dementia history may also contribute to poor functional and cognitive capacities. Stratified analyses showed that non-Hispanic white has similar results to the analytic population. Because of group size, other race/ethnic groups do not show statistically significant associations, but the point estimate directions are similar to the analytic population except for gender. Sensitivity analysis results were similar to that of the primary analysis. Conclusion Older U.S. individuals with cancer history have reduced functional capacities but not cognitive capacity compared to older U.S. individuals without cancer history. More research is needed to study these differences and how to improve older cancer survivors’ functional capacity, therefore optimizing health in elderly cancer survivors.