Date of Award
Open Access Dissertation
Epidemiology and Biostatistics
Lung cancer is the leading cause of cancer-related deaths in the United States with a 5-year survival rate of only 18%. Differences in access to care and treatment utilization may play a role in observed survival disparities among rural patient populations. This dissertation aimed to examine rural disparities in all-cause and lung-cancer specific survival, time to treatment initiation, and utilization of surgical treatment among non-small cell lung cancer cases.
We utilized comprehensive cancer registry data from the Surveillance, Epidemiology, and End Results program linked with Medicare billing claims (SEER-Medicare) for non-small cell lung cancer (NSCLC) patients diagnosed between 2003-2011. We compared differences in all-cause survival and lung cancer-specific survival based on urban and rural residence while controlling for demographic and clinical characteristics of patients. We examined differences in the time between diagnosis and treatment initiation for urban and rural NSCLC patients and furthermore the impact of time to treatment on survival. We also implemented multilevel modeling techniques to assess the associations of county-level neighborhood and patient-level demographic and clinical characteristics with utilization of surgical treatment in early-stage NSCLC patients.
Our results showed that rural NSCLC patients had worse all-cause and lung cancer-specific survival than their urban counterparts. Our adjusted Cox PH model results found that differences in the time between diagnosis and treatment initiation may not contribute to rural disparities in lung cancer survival. However, utilization of surgical treatment at any time point was related with high survival probability. More than 50% of the patients who received surgery survived longer than 5 years following diagnosis. When examining differences in surgical utilization, factors related to decreased likelihood of surgical treatment for lung cancer included living in higher poverty counties, enrollment in Medicaid, and black race. When controlling for county-level poverty and patient characteristics, rurality was not significantly related to differences in surgical utilization among NSCLC patients.
This dissertation identified persisting rural disparities in all-cause and lung cancer-specific survival in the United States. Observed rural disparities may be due to sociodemographic factors more common among rural cancer patients such as public insurance or being uninsured, and low incomes. In concordance with previous research, black NSCLC patients were also less likely than white patients to receive surgical treatment. Targeted interventions are needed to improve lung cancer survival in rural, low income, and black patient populations, particularly focusing on improving utilization of surgical treatment in early-stage cases among these groups.
Odahowski, C. L.(2019). Disparities in Non-Small Cell Lung Cancer in the United States: An Examination of Treatment, Survival, and Access to Care. (Doctoral dissertation). Retrieved from https://scholarcommons.sc.edu/etd/5446