“…Stereotactic Ablative Radiotherapy (SABR) is currently recognized as the gold standard for patients with inoperable stage I non-small cell lung cancer (NSCLC) [1]. This recommendation is based on the results of several prospective phase II trials [2], [3], [4], [5] and [6], as well as large observational studies [7], [8] and [9], with variable follow-up intervals: most of them were limited to spirometric parameters and diffusing capacity for carbon monoxide (Diffusion Lung capacity for Carbon monoxide, D L CO).…”