68IN - Stereotactic Ablative Radiotherapy in Early Stage Nsclc

Abstract

ABSTRACT SABR for lung tumors is defined by use of accurate radiotherapy delivery, and high radiation doses delivered in 8 or fewer fractions. In patients who are unfit to undergo surgery, or who refuse an operation, ESMO guidelines recommend SABR as the treatment of choice, with a biological dose of at least 100 Gy delivered to the encompassing isodose [Vansteenkiste J, 2013]. Dose fractionation schedules are often ‘risk adapted’, which implies use of a lower radiation doses/ fraction for tumors abutting normal organs such as the chest wall or hilar blood vessels. Toxicity after SABR is uncommon, with radiation pneumonitis, chest wall pain and rib fractures being reported in 10% of fewer of patients in most series [Senan S, 2014]. Loss of lung function after SABR is limited, even in patients with poor pulmonary function [Guckenberger M, 2012; Stanic S, 2014]. However, patients with pre-existing interstitial lung disease have a higher incidence of symptomatic and fatal radiation pneumonitis [Senan S, 2014]. Evidence in support of the use of SABR in early-stage NSCLC comes mainly from population studies [Haasbeek CJ, 2012; Shirvani SM, 2012]. Data from two prospective randomized studies comparing SABR to conventionally-fractionated radiotherapy are awaited, but access to short, outpatient SABR treatment has reduced the rates of non-treatment in elderly patients. In patients who are at high-risk for surgical complications, as well as those at high risk for competing causes of mortality, the advantages of SABR are sufficiently evident as to merit informing all patients of this option [Palma D, 2013]. Three prospective randomized trials that compared SABR and surgery in operable cases have closed prematurely. The available data from 9 comparative effectiveness studies comparing SABR and surgery range from match-pair and propensity scoring analyses, Markov modeling, systematic reviews and retrospective series. Such data must be critically evaluated in the light of their strengths and weakness. Disclosure: S. Senan has received speakers honoraria and research support from Varian Medical Systems.