Development and external validation of a nomogram to predict overall survival following stereotactic body radiotherapy for early-stage lung cancer

Sarah Baker,Wilma D Heemsbergen,Imogeen Antonisse,Robin Cornelissen,John Praag,Joost Jan Nuyttens,Katerina Bakunina,Mischa S Hoogeman,Marloes Duijm

doi:10.1186/s13014-020-01537-z

Sarah Baker, Wilma D Heemsbergen + Show 7 more

Open Access

https://doi.org/10.1186/s13014-020-01537-z

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Abstract

BackgroundPrognostication tools for early-stage non-small cell lung cancer (NSCLC) patients treated with stereotactic body radiotherapy (SBRT) are currently lacking. The purpose of this study was to develop and externally validate a nomogram to predict overall survival in individual patients with peripheral early-stage disease.MethodsA total of 587 NSCLC patients treated with biologically effective dose > 100 Gy10 were eligible. A Cox proportional hazards model was used to build a nomogram to predict 6-month, 1-year, 3-year and 5-year overall survival. Internal validation was performed using bootstrap sampling. External validation was performed in a separate cohort of 124 NSCLC patients with central tumors treated with SBRT. Discriminatory ability was measured by the concordance index (C-index) while predictive accuracy was assessed with calibration slope and plots.ResultsThe resulting nomogram was based on six prognostic factors: age, sex, Karnofsky Performance Status, operability, Charlson Comorbidity Index, and tumor diameter. The slope of the calibration curve for nomogram-predicted versus Kaplan-Meier-estimated overall survival was 0.77. The C-index of the nomogram (corrected for optimism) was moderate at 0.64. In the external validation cohort, the model yielded a C-index of 0.62.ConclusionsWe established and validated a nomogram which can provide individual survival predictions for patients with early stage lung cancer treated with SBRT. The nomogram may assist patients and clinicians with treatment decision-making.

Highlights

Prognostication tools for early-stage non-small cell lung cancer (NSCLC) patients treated with stereotactic body radiotherapy (SBRT) are currently lacking
The purpose of this study was to identify prognostic factors for survival in early lung cancer patients treated with SBRT and to build a nomogram to predict 6-month, 1year, 3-year and 5-year overall survival
Two-hundred and fiftyeight patients had biopsy confirmation of disease, while the remaining 329 had an FDG-avid lesion on positron emission tomography (PET) deemed highly suspicious of NSCLC upon multidisciplinary tumor board review

Summary

Introduction

Prognostication tools for early-stage non-small cell lung cancer (NSCLC) patients treated with stereotactic body radiotherapy (SBRT) are currently lacking. Stereotactic body radiotherapy (SBRT) is the standard of care for medically inoperable early-stage non-small cell lung cancer (NSCLC) [1]. It is increasingly utilized in the high risk operable patient population [2]. A major contributor to survival variability is the potentially high rate of competing non-cancer mortality. Severe chronic obstructive pulmonary disease (COPD), common in the SBRT lung population, is associated with a 70% mortality rate at 5 years in those with 3 or more acute exacerbations [5]. Despite high rates of local control and cancer-specific survival, overall survival (OS) remains poor and in the order of 40% at 5 years [2]

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