A population-based study of the diagnosis to treatment interval and overall survival for stage I non-small cell lung cancer treated with stereotactic body radiation therapy
TL;DR
The findings suggest that efforts to shorten DTI may improve patient survival in this population of patients with stage I non-adenocarcinoma NSCLC treated with SBRT in Ontario.
Abstract
Background: Lung cancer is one of the most diagnosed cancers and the leading cause of cancer-related deaths in Ontario. For patients with medically inoperable stage I non-small cell lung cancer (NSCLC), stereotactic body radiation therapy (SBRT) is recommended. However, there is limited evidence on how the diagnosis to treatment interval (DTI) impacts survival, which is relevant to inform health policy and improve patient outcomes. Objective: To investigate the association between DTI and survival for patients with stage I non-adenocarcinoma NSCLC treated with SBRT in Ontario. Methods: We conducted a population-based retrospective cohort study using linked ICES health administrative datasets, applying recently published international consensus-based methodology recommendations for investigating the association between cancer DTI and overall survival (OS). The cohort included Ontario patients with stage I NSCLC diagnosed between January 1, 2010, and June 30, 2019, treated with curative SBRT. Patients with adenocarcinomas were excluded because of histological diversity uncontrollable within the available data. A 5 month from diagnosis landmark time was used to limit immortal time bias and the wait time paradox. Kaplan Meier analysis was used to visualize survival. Multivariable Cox proportional hazards models were used to assess the association between DTI and OS and cancer-specific survival (CSS), adjusting for relevant factors. Results: The cohort included 532 patients with a median DTI of 61 (interquartile range: 46-79) days. Kaplan Meier analysis suggested longer DTIs were associated with worse OS. In adjusted Cox models, each 1-week (aHR=1.04 (95% CI=1.01–1.08)), and 4-week (aHR=1.19 (95% CI=1.03–1.38)) increase in DTI was associated with worse OS. Similarly, each 1-week (aHR=1.05 (95% CI=1.01–1.10)), and 4-week (aHR=1.22 (95% CI=1.03–1.45)) increase in DTI was associated with worse CSS. Findings remained robust in sensitivity analyses. Conclusions: Our findings suggest that efforts to shorten DTI may improve patient survival in this population.