Abstract
INTRODUCTION: Rural-urban disparities persist in cancer mortality, despite improvement in cancer screening and treatment. Although older adults represent the majority of cancer cases and are over-represented in rural areas, few studies have explored rural-urban disparities in mortality and age-related impairments among older adults with cancer. MATERIALS AND METHODS: We included 962 newly-diagnosed older adults (≥60 years) with cancer who underwent geriatric assessment (GA) at their first pre-chemotherapy visit to an academic medical center in the Southeastern United States. We used Rural-Urban Commuting Area (RUCA) codes to classify residence at time of diagnosis into urban and rural areas. We used one-year survival and pre-treatment frailty as outcomes. We used Cox proportional hazards regression to evaluate the association between residence and one-year mortality, and logistic regression to evaluate the association between residence and pre-treatment frailty. All tests were two-sided. RESULTS: Median age at GA was 68.0 (interquartile rage [IQR]: 64.0, 74.0) years; most had colorectal cancer (24.3%) with advanced stage (III/IV 73.2%) disease. Overall, 11.4% resided in rural and 88.6% in urban areas. Rural areas had a higher proportion of White and less educated participants. After adjustment for age, sex, race, education, employment status, and cancer type/stage, rural residence was associated with higher hazard of one-year mortality (hazard ratio [HR] = 1.78, 95% confidence interval [CI] = 1.23, 2.57) compared to urban residence. Frailty was an effect modifier of this association (HR(Overall) = 1.83, 95% CI = 1.27, 2.57; HR(Frail) = 2.05, 95% CI = 1.23, 3.41; HR(Not Frail) = 1.55, 95% CI = 0.90, 2.68). DISCUSSION: Among older adults with newly diagnosed cancer, rural residence was associated with reduced one-year survival, particularly among frail older adults. The rural-urban disparities observed in the current study may be due to frailty in conjunction with disparities in social determinants of health across rural and urban areas. Future studies should focus on understanding and intervening on underlying causes of these disparities.