Racial disparities in treatment patterns and survival outcomes for patients diagnosed with advanced non-small cell lung cancer before and after approval of immune checkpoint inhibitors: A population-based study

BackgroundLung cancer is the second most diagnosed cancer and the leading cause of cancer death in the United States. Non–small cell lung cancer (NSCLC) accounts for 80–90% of cases and is frequently diagnosed at advanced stages, producing a poor prognosis. Immune checkpoint inhibitors (ICIs), introduced in 2015, transformed systemic therapy for advanced NSCLC, but their cost and delivery can reinforce or reshape disparities in access, utilization, and outcomes. Before ICI adoption, racial and ethnic disparities in lung cancer care were documented; assessing whether these persisted after ICI rollout is essential to understanding population-level impact after introduction of these novel therapies. Objectives and Specific AimsThis dissertation examined racial differences in systemic anticancer therapy use and overall survival (OS) before (pre-ICI) and after (post-ICI) ICI approval, and evaluated factors associated with ICI receipt. Specific aims are: (1) Describe disparities in receipt of systemic anticancer treatment by line of therapy and therapy type for White, Black, and Asian advanced NSCLC patients in pre- and post-ICI periods. (2) Identify factors associated with ICI receipt among advanced NSCLC patients in the post-ICI era. (3) Assess disparities in overall survival and lung cancer-specific survival comparing the post-ICI to pre-ICI time period for White, Black, and Asian patients. MethodsThe Surveillance, Epidemiology, and End Results (SEER)-Medicare database was leveraged for this study. Patients included were aged ≥65 with advanced NSCLC (stage IIIB–IV) diagnosed between 2011 and 2019; exclusions included: age <65, missing race, patients other than White, Black and Asian race groups, concomitant cancers, incomplete Medicare Parts A/B coverage in the 12 months before diagnosis, diagnoses at autopsy, nursing home residents, or identified only by death certificate. Index dates were diagnosis dates (studies 1 and 3) or first-line therapy initiation dates (study 2). Follow-up extended to death, loss of coverage, or December 31, 2020.Study 1 compared pre-ICI (2011–2014) and post-ICI (2015–2019) treatment patterns by race group and therapy class. Study 2 classified patients in the post-ICI period by receipt of ICI therapy during the study period. Predictors of ICI use were assessed in logistic regression and adjusted OS among ICI recipients using Cox proportional hazards models, adjusting for key covariates. Study 3: used truncated cohorts (pre: 2011–2013; post: 2016–2018) to evaluate differences in OS and lung cancer-specific survival (LCSS) by race across and within the time periods. Stabilized inverse probability of treatment weights (IPTW) were applied, and weighted Cox proportional hazards models estimated the effect of time period on survival. ResultsStudy 1 showed an increased uptake of immunotherapy in the post ICI era; however, roughly half of older patients with advanced NSCLC received no systemic anticancer therapy in either era, with Black patients least likely to receive treatment and experiencing the longest delays to treatment initiation. Study 2 found ICI use increased substantially after 2015, but Black and Asian patients were less likely to receive ICI compared to White patients; among those who did receive ICI, adjusted survival did not differ by race. In study 3, after IPTW weighting to balance cohorts, OS was worse for all three races in the post ICI time period. However, after adjusting for receipt of systemic anti-cancer therapy and restricting to patients who received systemic anti-cancer therapy, OS slightly improved for White patients, with no difference for Black patients, and slightly worsened for Asian patients. LCSS was better in the post-ICI period compared to the pre-ICI period for all three race groups.ConclusionsICIs are changing advanced NSCLC care, but real-world benefits are shaped by unequal uptake, patient factors, and systemic barriers. Treatment initiation increased across all race groups, but Black patients were less likely to receive therapy and face longer delays. While Black and Asian patients were less likely to receive ICI, survival among ICI recipients was similar by race, implying comparable effectiveness when access is equitable. As well, nearly half of older patients remained untreated. Addressing underutilization, treatment delays, and access disparities — and improving minority representation in trials — is essential to ensure equitable population-level benefit from novel therapies.