Improved Survival Outcomes in Medically Fit Patients With Early-Stage Non-Small-Cell Lung Cancer Undergoing Stereotactic Body Radiotherapy

Sins of omission: A meta-research study evaluating the omission of operability in published retrospective comparisons of surgery with stereotactic body radiotherapy in patients with early-stage non-small cell lung cancer

INTRODUCTION

Patients receiving stereotactic body radiotherapy (SBRT) for early-stage non-small cell lung cancer (NSCLC) are typically inoperable, in concordance with guidelines that advocate surgical resection as preferred treatment for operable patients. This differential treatment allocation complicates retrospective comparisons of surgery with SBRT by introducing the potential for confounding by operability.

METHODS

PubMed was queried for manuscripts reporting primary data from retrospective comparisons of overall survival (OS) between patients undergoing surgery versus SBRT for early-stage NSCLC. Each manuscript was categorized for two outcomes: (1) whether treatment allocation was based on a determination of patient operability, and (2) whether a direct OS comparison between operable SBRT patients and surgically treated patients was included. Associations with variables of interest were measured with statistical significance prespecified at p < 0.10.

RESULTS

From 3,072 manuscripts identified in our query, sixty-one analyses met screening criteria. Twenty-one (34 %) reported operability status influencing treatment allocation. These were more likely to be published in journals with a surgical focus (52 vs 20 %) and impact factor < 5 (81 vs 58 %), and to contain cohorts from institutional datasets (81 vs 55 %), and to have a radiation oncologist as first (43 vs 25 %) or senior (43 vs 28 %) author. Seven (11 %) manuscripts featured a direct OS comparison between SBRT and surgery.

CONCLUSION

Nearly-two-thirds of peer-reviewed retrospective studies that have compared OS between surgery and SBRT for early-stage NSCLC lack information on patient operability status, and nearly 90% lack a direct comparison between operable SBRT patients and those receiving surgery.

The impact of operability status on outcomes in patients with T4 larynx cancer undergoing larynx preservation

BACKGROUND

Large analyses of T4 larynx cancer (LC) have raised concerns that larynx preservation (LP) contributes to reduced survival compared with laryngectomy (LGX). The role of operability has not been previously considered as a confounder.

METHODS

We queried the National Cancer Database for T4M0 LC diagnosed 2004-2015. Patients were categorized as undergoing LGX, chemoradiotherapy but operable (LP-operable), and chemoradiotherapy inoperable (LP-inoperable). Overall survival (OS) was estimated by Kaplan-Meier. Cox multivariate analysis (MVA) identified variables associated with OS.

RESULTS

We identified 1405 LGX, 164 LP-operable and 1969 LP-inoperable patients. Compared with LGX, MVA demonstrated worse OS among LP-inoperable (HR 1.28 95%CI 1.17-1.40, p < 0.01) but not LP-operable patients (HR 1.12 95%CI 0.91-1.39, p = 0.28).

CONCLUSIONS

LP-operable patients did not have significantly worse OS than those undergoing LGX.

Association of Operability with Post-Treatment Mortality in Early-Stage Non-Small Cell Lung Cancer

BACKGROUND

Operability is both a crucial determinant in treatment selection and a potential confounder in analyses comparing surgery with non-surgical approaches such as stereotactic body radiotherapy (SBRT). We aimed to assess the association between operability status and intervention with post-treatment mortality in early-stage non-small cell lung cancer (NSCLC).

PATIENTS AND METHODS

We defined four groups of patients with cT1-T2N0M0 NSCLC diagnosed 2010 to 2014 from the National Cancer Database: SBRT patients deemed operable vs. inoperable and surgery patients receiving open vs. minimally-invasive approaches. Mortality rates at 30, 60, and 90 days post-treatment were calculated and compared.

RESULTS

We abstracted 80,108 patients, 0.8% undergoing SBRT and operable, 13.2% undergoing SBRT and inoperable, 52.4% undergoing open surgery, and 33.7% undergoing minimally-invasive surgery. Mortality rates were highest among open surgery patients and lowest among operable SBRT patients (2.0% vs. 0.2% at 30 days and 3.7% vs. 0.7% at 90 days), with intermediate results in the other two groups. These findings persisted on multivariate Cox regression: compared to patients undergoing minimally-invasive surgery, mortality risk was highest among open surgery patients (30 days HR 1.32, 95%CI 1.16-1.51; 90 days HR 1.36, 95%CI 1.24-1.50; both P < .001) and lowest among operable SBRT patients (30 days HR 0.09, 95%CI 0.01-0.64; 90 days HR 0.15, 95%CI 0.05-0.46; both P ≤ .016). These associations were maintained in a propensity score-matched subset.

CONCLUSION

Operable patients undergoing SBRT experience minimal post-treatment mortality compared to their inoperable counterparts. These findings illustrate the potential for confounding by operability to bias results in cohort studies that compare surgical vs. non-surgical approaches in early-stage NSCLC.