Outcomes in stage I non-small cell lung cancer following the introduction of stereotactic body radiotherapy in Alberta - A population-based study.

Abstract

To review outcomes of patients with stage I non-small cell lung cancer (NSCLC) following the introduction of stereotactic body radiation therapy (SBRT). SBRT cases were linked to the cancer registry database along with clinical, treatment and health service parameters for n=2146 cases of stage I NSCLC diagnosed between 2005 and 2011. The pre-diagnosis Aggregated Clinical Risk Grouping score (ACRG3) was used as a proxy for pre-treatment patient comorbidity. A Cox regression model and the concordance statistic (C-statistic) were used to examine variables predicted for overall survival (OS). The SBRT utilization rate increased annually with superior OS to conventional RT (median survival [MS] of 39.4 VS. 23.5months, P<0.001) despite higher ACRG3 scores. Surgical patients were younger, had lower ACRG3, achieving MS of 69.6months. Regression analysis indicated both Surgery (hazard ratio [HR]=0.23, 95% CI: 0.18-0.28) and SBRT (HR=0.33, 95% CI: 0.21-0.51) remained most strongly associated with OS. ACRG3 (HR=0.79, P<0.001) and age (HR=0.83, P=0.03) were independently associated with OS. The OS model was associated with the C-statistic at 0.86, 95% CI: 0.81-0.90. In stage I NSCLC patients treated with surgery have the best survival. SBRT demonstrates improved OS compared to conventional RT. C-statistic result demonstrates discrimination of treatment selection factors on OS.