Background and purpose: Stereotactic ablative radiotherapy (SABR) has become standard for inoperable early-stage non-small cell lung cancer (NSCLC). However, there is no randomized evidence demonstrating benefit over more fractionated radiotherapy. We compared accelerated hypofractionation (AH) and SABR using a propensity score-matched analysis.
Materials and methods: From 1997-2007, 119 patients (T1-3N0M0 NSCLC) were treated with AH (48-60 Gy, 12-15 fractions). Prior to SABR, this represented our institutional standard. From 2008-2012, 192 patients (T1-3N0M0 NSCLC) were treated with SABR (48-52 Gy, 4-5 fractions). A total of 114 patients (57 per cohort) were matched (1:1 ratio, caliper: 0.10) using propensity scores.
Results: Median follow-up (range) for the AH cohort was 36.3 (2.5-109.1) months, while that for the SABR group was 32.5 (0.3-62.6)months. Three-year overall survival (OS) and local control (LC) rates were 49.5% vs. 72.4% [p=0.024; hazard ratio (HR): 2.33 (1.28, 4.23), p=0.006] and 71.9% vs. 89.3% [p=0.077; HR: 5.56 (1.53, 20.2), p=0.009], respectively. On multivariable analysis, tumour diameter and PET staging were predictive for OS, while the only predictive factor for LC was treatment cohort.
Conclusions: OS and LC were improved with SABR, although OS is more closely related to non-treatment factors. This represents one of the few studies comparing AH to SABR for early-stage lung cancer.
Keywords: Accelerated hypofractionation; Lung cancer; Stereotactic radiotherapy.
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