Mortality after radiotherapy or surgery in the treatment of early stage non-small-cell lung cancer: a population-based study on recent developments

Abstract

Stereotactic body radiotherapy (SBRT) can achieve high tumour control with limited toxicity for inoperable early stage non-small-cell lung cancer (NSCLC) patients. The German Epidemiologic Cancer Registries from the Robert-Koch Institute were assessed. Periods according to the availability of SBRT were: (1) 2000–2003 (pre-SBRT); (2) 2004–2007 (interim); and (3) 2007–2014 (broad availability of SBRT). To assess the association of cancer-related parameters with mortality, hazard ratios (HR) from Cox proportional hazards models were computed. To evaluate the change of treatment-related mortality, we performed interaction analyses and the relative excess risk due to interaction (RERI, additive scale) was computed. A total of 16,292 patients with UICC stage I NSCLC diagnosed between 2000 and 2014 were analysed. Radiotherapy utilization increased from 5% in pre-SBRT era to 8.8% after 2007. In univariate analyses, survival in the whole cohort improved only marginally when 2000–2003 is compared to 2004–2007 (HR 0.92, 95% CI 0.85–1.01) or 2008–2014 (HR 0.93, 95% CI 0.86–1.01). Comparing surgery/radiotherapy, mortality in the radiotherapy group started from a 3.5-fold risk in 2000–2003 to 2.6 after 2007. The interaction analysis revealed a stronger improvement for radiotherapy (multiplicative scale for 2000–2003 vs.\u2009>\u20092007: 0.74, 95% CI 0.58–0.94). On an additive scale, treatment\u2009×\u2009period interaction revealed an RERI for 2000–2003 vs.\u2009>\u20092007 of −\u20091.18 (95% CI −\u20091.8, −\u20090.55). Using population-based data, we observed a survival improvement in stage I lung cancer over time. With an increasing utilization of radiotherapy, a stronger improvement occurred in patients treated with radiotherapy when compared to surgery.