Date of Award

January 2023

Document Type


Degree Name

Master of Public Health (MPH)


School of Public Health

First Advisor

Shi-yi Wang


Background: Patients diagnosed with advanced non-small cell lung cancer (NSCLC) have a poor prognosis. To inform evidence-based care, this study aims to describe and quantify the first-line treatment variation of patients with NSCLC. Methods: A retrospective cohort study was conducted using Flatiron databases to analyze the treatment patterns of 18,979 patients with advanced NSCLC diagnosed between 1/1/2016 and 6/30/2020. Patients were categorized into groups by biomarker findings and performance status. The first-line treatment variations were measured using the Herfindahl-Hirschman Index (HHI), which provides an indication of the degree of variation in treatment. Bootstrapping was assisted in calculating 95% confidence intervals for the HHI scores for overall and subgrouped patients. Results: Among the patients included, 397 had ALK-positive NSCLC, 2,156 had EGFR-positive NSCLC, 4,217 had PD-L1 <1% NSCLC, 4,406 had PD-L1 1-49% NSCLC, and 3,661 had PD-L1 >=50% NSCLC. HHI score for first-line therapy choices in our analysis of 18,979 individuals with advanced NSCLC was 1740 [95% CI: 1021,3246], showing substantial treatment variance. We discovered that each biomarker status group showed considerably less variation than the all patients. In particular, the ALK and EGFR groups showed considerably higher HHI scores, 4261 and 4766, respectively, indicating less therapy variation in practice. The HHI values for the PD-L1 <1% and PD-L1 1-49% groups were only 2951 and 2777, respectively, indicating considerable treatment variance. We also looked at HHI scores for ECOG performance status subgroups without biomarker inhibitors. We found no significant difference in HHI scores for first-line treatment between the all patients and the ECOG performance status subgroups. Conclusion: Despite the availability of treatment guidelines, there is a lack of consistent first-line therapy patterns among physicians treating patients with advanced NSCLC. The high level of first-line treatment variation identified in patients with PD-L1 <1% and 1-49% highlights the need to improve the selection and standardization of first-line therapy for these patients. These findings have important implications for optimizing patient care and improving treatment outcomes.


This thesis is restricted to Yale network users only. It will be made publicly available on 05/10/2025