Stereotactic ablative radiotherapy (SABR) for central lung tumors: Plan quality and long-term clinical outcomes

Abstract

Background and purposeCentral lung SABR is less established due to toxicity concerns. We describe plan quality and clinical outcomes for patients treated with VMAT SABR using 8×7.5Gy. Materials and methodsWe studied 80 consecutive patients with primary NSCLC and PTV ⩽2cm from the proximal bronchial tree (PBT), treated between 2008 and 2013. Dosimetric data were compared with institutional guidelines and study protocols, and long-term clinical outcomes were analyzed. ResultsPTV V95% was 60Gy in 96% of patients. Dmax was ⩾60Gy in 40% of patients for PBT, 26.3% for aorta, 55% for heart, and 1.3% for trachea. Esophageal maximum Dmax was 58Gy. Mean lung V5Gy/V20Gy was 21/8%. 54 patients (68%) exceeded RTOG0813 Dmax for ⩾1 organ-at-risk (OAR), with 27 exceeding PBT Dmax. 5 of 78 patients (6.4%) with adequate follow-up information had grade 3 toxicity. Grade 4 toxicity was not observed. Treatment-related death was considered possible (n=3) or likely (n=3) in 6 patients (7.5%). With median follow-up of 47months, 3-year survival was 53%, compared with 57% for 252 peripheral tumors treated with 3/5-fractions SABR in the same period (p=0.369). ConclusionsAlthough a substantial proportion of central SABR patients received ⩾60Gy to OARs, the 3-year survival was no different from peripheral SABR.