A Multilevel Mixed Methods Examination of Treatment Nonadherence Among Rural Cancer Survivors

While mortality rates have been decreasing over the last 40 years, cancer remains a leading cause of death in the United States. Over 1.7 million people were diagnosed with cancer in 2019, and there were more than 600,000 cancer deaths. Of the 15 million cancer survivors in the US, nearly 3 million reside in rural areas and experience 3% higher cancer incidence and 10% higher cancer mortality compared to their nonrural counterparts. During 2006-2015, the annual age-adjusted mortality rates for all cancer sites combined decreased at a slower pace in rural areas versus nonrural areas (-1.0% vs -1.6% per year, respectively), widening the disparity in mortality rates. Although the reasons for these disparities are not fully known, rural cancer survivors tend to be older, have additional comorbidities and poorer general health, and have a higher prevalence of lifestyle risk factors, such as smoking and lack of physical activity, that complicate survival and may contribute to the higher mortality rate. Nonadherence to cancer treatment is associated with poorer cancer outcomes, including higher rates of cancer recurrence or treatment failure and decreased survival. Reports of mortality have been up to four times as likely in nonadherent compared with adherent survivors. A growing set of studies have begun to document that cancer treatment adherence is poorer among rural populations, which may also partially explain the higher mortality rate observed in rural areas. This dissertation is comprised of three studies: 1) a systematic review of the role of digital health in rural oncology; 2) a data analysis of hospital and billing claims data examining geographic differences in sociodemographic and clinical factors associated with radiation treatment nonadherence; and 3) a multilevel, theory-driven examination of rural cancer treatment nonadherence utilizing survey and individual interview data