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ESTRO 2020

Session Item

Poster highlights 9 CL: Lung
8080
Poster Highlights
Clinical
09:01 - 09:09
Schedule of irradiation impacts the overall survival in case of SBRT for stage I NSCLC
Loïg Duvergé, France
PH-0278

Abstract

Schedule of irradiation impacts the overall survival in case of SBRT for stage I NSCLC
Authors: Julien Bellec.(Centre Eugène Marquis, Radiotherapy, Rennes, France), Pierre-Yves Bondiau.(Centre Antoine Lacassagne, Radiotherapy, Nice, France), Joël Castelli.(Centre Eugène Marquis, Radiotherapy, Rennes, France), Enrique Chajon.(Centre Eugène Marquis, Radiotherapy, Rennes, France), Line Claude.(Centre Léon Bérard, Radiotherapy, Lyon, France), Renaud de Crevoisier.(Centre Eugène Marquis, Radiotherapy, Rennes, France), Jérôme Doyen.(Centre Antoine Lacassagne, Radiotherapy, Nice, France), Loïg Duvergé.(Centre Eugène Marquis, Radiotherapy, Rennes, France), Charles Ricordel.(Centre Hospitalier Universitaire, Pneumology, Rennes, France), Ingrid Sidibe.(Institut de Cancérologie de l'Ouest Centre René Gauducheau, Radiotherapy, Saint-Herblain, France), Stéphane Supiot.(Institut de Cancérologie de l'Ouest Centre René Gauducheau, Radiotherapy, Saint-Herblain, France), François Thillays.(Institut de Cancérologie de l'Ouest Centre René Gauducheau, Radiotherapy, Saint-Herblain, France), Loïg Vaugier.(Institut de Cancérologie de l'Ouest Centre René Gauducheau, Radiotherapy, Saint-Herblain, France)
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Purpose or Objective

In the context of stereotactic body radiotherapy (SBRT) for early stage non-small cell lung cancer (NSCLC), the objective of our study was to determine the impact on local control (LC) and overall survival (OS) of a continuous versus discontinuous schedule of radiotherapy.

Material and Methods

A total of 490 consecutive NSCLC stage I patients treated in 4 French radiation oncology centers between January 2008 and July 2018, were retrospectively analyzed. The prescribed dose ranged from 30 to 75 Gy in 3 to 10 fractions with a median biologically effective dose of 125 Gy (α/β = 10 Gy). Based on the ratio between the treatment duration (TD) and the number of fractions (n), patients were divided into two groups: continuous (TD < 2n) versus discontinuous (TD ≥ 2n) schedule. Local control, overall survival and toxicity were compared using Cox regression analyses. In order to limit any differences between the two groups at baseline, a 1:1 propensity score matching (nearest neighbor matching algorithm, caliper distance of 0.2) was performed.

Results

The median follow-up was 41 months. The median age was 74 years old. Two hundred and forty-five patients were treated according to the continuous regimen and 245 to the discontinuous regimen. The two groups were comparable in terms of the major potential confounding factors. The 3-year LC was 92% for the discontinuous treatment versus 84% for the continuous one (p = 0.0017) (Figure 1), with a Hazard Ratio (HR) of 0.48 (CI 95% 0.26-0.89). The 3-year OS was 64% for the discontinuous treatment versus 52% for the continuous one (p = 0.0024) (Figure 2), HR of 0.66 (CI 95% 0.5-0.86). 216 patient pairs were identified with propensity score matching. Discontinuous treatment schedule was still associated with better overall survival with a HR of 0.64 (95% CI 0.48 – 0.85), p = 0.0029 and better local control with a HR of 0.39 (95% CI 0.19 – 0.79), p = 0.0089. In multivariate analysis, only the irradiation schedule and the number of fractions were correlated with LC. The irradiation schedule, age, WHO performance status and T stage were significantly correlated with OS. Less than 2% of acute or post-treatment grade 3 pulmonary toxicity was reported for both groups.

Conclusion

Our study is the first to show a positive impact of a discontinuous versus continuous schedule on overall survival as well as on local control for early stage NSCLC treated by SBRT, with similar low profile of toxicity. A multicenter randomized prospective study will be started in order to validate our results.