Impact of Lung Parenchymal-Only Failure on Overall Survival in Early-Stage Lung Cancer Patients Treated With Stereotactic Ablative Radiotherapy

Abstract

Introduction: The impact of lung parenchymal-only failure on patient survival after stereotactic ablative body radiotherapy (SABR) for early-stage non-small-cell lung cancer (NSCLC) remains unclear.

Patients and methods: The study population included 481 patients with early-stage NSCLC who were treated with 3- to 5-fraction SABR between 2000 and 2016. The primary study objective was to assess the impact of out-of-field lung parenchymal-only failure (OLPF) on overall survival (OS).

Results: At a median follow-up of 5.9 years, the median OS was 2.7 years for all patients. Patients with OLPF did not have a significantly different OS compared to patients without failure (P = .0952, median OS 4.1 years with failure vs. 2.6 years never failure). Analysis in a 1:1 propensity score-matched cohort for Karnofsky performance status, comorbidity score, and smoking status showed no differences in OS between patients without failure and those with OLPF (P = .8). In subgroup analyses exploring the impact of time of failure on OS, patients with OLPF 6 months or more after diagnosis did not have significantly different OS compared to those without failure, when accounting for immortal time bias (P = .3, median OS 4.3 years vs. 3.5 years never failure). Only 7 patients in our data set experienced failure within 6 months of treatment, of which only 4 were confirmed to be true failures; therefore, limited data are available in our cohort on the impact of OLPF for ≤ 6 months on OS.

Conclusion: OLPF after SABR for early-stage NSCLC does not appear to adversely affect OS, especially if occurring at least 6 months after SABR. More studies are needed to understand if OLPF within 6 months of SABR is associated with adverse OS. These data are useful when discussing prognosis of lung parenchymal failures after initial SABR.

Trial registration: ClinicalTrials.gov NCT02468024 NCT02629458 NCT01753414 NCT02984761.

Keywords: NSCLC; Recurrence; SABR; SBRT; Salvage.

Copyright © 2020 Elsevier Inc. All rights reserved.

Figures

Figure 1

A Overall Survival in Patients with Lung Parenchymal Failure Compared to Patients Who Never Failed B Overall Survival in Patients with and without Lung Parenchymal Failure after One-to-One Propensity Score Matching Patients were one-to-one matched on KPS, pack years, and Charlson Comorbidity Index. The matching process yielded 29 matched pairs.

Figure 1

A Overall Survival in Patients with Lung Parenchymal Failure Compared to Patients Who Never Failed B Overall Survival in Patients with and without Lung Parenchymal Failure after One-to-One Propensity Score Matching Patients were one-to-one matched on KPS, pack years, and Charlson Comorbidity Index. The matching process yielded 29 matched pairs.

Figure 2

A Overall Survival Comparing Time to Lung Parenchymal Failure B Overall Survival in Patients with Lung Parenchymal Failure Compared to Patients Who Never Failed (at least 2 years of follow-up)

Figure 2

A Overall Survival Comparing Time to Lung Parenchymal Failure B Overall Survival in Patients with Lung Parenchymal Failure Compared to Patients Who Never Failed (at least 2 years of follow-up)

Figure 3

Overall Survival in Patients with In-Field Failure Compared to Patients with Lung Parenchymal Failure

Figure 4

Overall Survival Comparing Patients with Lung Parenchymal Failure and Patients with Metastasis