Prognostic factors of local control and disease free survival in centrally located non-small cell lung cancer treated with stereotactic body radiation therapy

Marloes Duijm,Noëlle C Van Der Voort Van Zyp,Patrick V Granton,Paul Van De Vaart,Mirjam E Mast,Esther Oomen-De Hoop,Mischa S Hoogeman,Joost J Nuyttens

doi:10.1080/0284186x.2020.1750693

Marloes Duijm, Noëlle C Van Der Voort Van Zyp + Show 6 more

Open Access

https://doi.org/10.1080/0284186x.2020.1750693

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Journal: Acta Oncologica	Publication Date: Apr 14, 2020
Citations: 4	License type: open-access

Affiliation: Erasmus MC Cancer Institute, GGD Haaglanden

Abstract

Background: Stereotactic body radiation therapy (SBRT) results in high local control (LC) rates in patients with non-small cell lung cancer (NSCLC). For central lung tumors, risk-adapted fractionation schedules are used and underdosage to the Planned Target Volume (PTV) is often accepted to respect the dose constraints of the organs at risk in order to avoid high rates of toxicity. The purpose of this study was to analyze the effect of PTV underdosage and other possible prognostic factors on local- and disease control after SBRT in patients with central lung tumors.Material and Methods: Patients with centrally located NSCLC treated with SBRT were included. The doses were converted into biologically equivalent dose using α/β-value of 10 Gy (BED10). Underdosage to the PTV was defined as the (percentage of) PTV receiving less than 100 Gy BED10; (%)PTV < 100 BED10. Potential prognostic factors for LC and Disease Free Survival (DFS) were evaluated using Cox regression analysis.Results: Two hundred and twenty patients received ≤12 fractions of SBRT. LC-rates were 88% at 2 years and 81% at 3 years. Twenty-seven patients developed a local recurrence. Both the PTV < 100 BED10 and %PTV < 100 BED10 were not prognostic for LC. Tumor size and forced expiratory volume in 1 second (FEV1) were independently prognostic for LC. Disease progression was reported in 75 patients with DFS-rates of 66% at 2 years and 56% at 3 years. Disease recurrence was independent significantly associated with larger tumor diameter, lower lobe tumor location and decreased FEV1. Grade 4–5 toxicity was reported in 10 patients (8 with ultra-central tumors) and was fatal in at least 3 patients.Conclusion: Decrease in tumor coverage was not correlated with the local recurrence probability. The LC and DFS were promising after SBRT of centrally located NSCLC with tumor size, FEV1 and tumor location (for DFS only) as prognostic factors.

Highlights

Stereotactic body radiation therapy (SBRT) is the golden standard in patients having early stage non-small cell lung cancer (NSCLC) not suitable for surgery [1,2]
Over more than 15 years ago, reports of high-grade toxicity after stereotactic radiotherapy resulted in the definition of a ‘central lung tumor’ together with the proposal of risk-adapted fractionation schedules [3,4] and accompanying dose constraints for organs at risk (OAR) [5]
Multiple studies report high local control (LC) rates when prescribing a minimum of 100 Gy BED10 [9,10,11,12]

Summary

Introduction

Stereotactic body radiation therapy (SBRT) is the golden standard in patients having early stage non-small cell lung cancer (NSCLC) not suitable for surgery [1,2]. Over more than 15 years ago, reports of high-grade toxicity after stereotactic radiotherapy resulted in the definition of a ‘central lung tumor’ together with the proposal of risk-adapted fractionation schedules [3,4] and accompanying dose constraints for organs at risk (OAR) [5]. Stereotactic body radiation therapy (SBRT) results in high local control (LC) rates in patients with non-small cell lung cancer (NSCLC). Risk-adapted fractionation schedules are used and underdosage to the Planned Target Volume (PTV) is often accepted to respect the dose constraints of the organs at risk in order to avoid high rates of toxicity.

Objectives

Methods

Conclusion