Precision Stereotactic Body Radiotherapy for Ultra-Central NSCLC: Tailored Margins Reduce Toxicity Without Compromising Tumor Control.

Abstract

Stereotactic body radiation therapy (SBRT) is effective for early-stage non-small cell lung cancer (NSCLC), but the treatment of ultra-central NSCLC (UCNLC) near critical structures remains challenging. This retrospective study analyzed 66 patients with stage I-II unresectable UCNLC who underwent SBRT at Shanghai Pulmonary Hospital (2020-2023). UCNLC was defined by planning target volumes (PTVs) abutting/overlapping vital structures (proximal bronchial tree, esophagus, heart, great vessels, pulmonary vessels) or internal target volumes (ITVs) within 1 cm of these organs. Tailored SBRT plans with non-uniform PTV margins were used in 45.5% of cases, enabling 53.3% of patients to receive a biologically effective dose ≥ 100 Gy. With a median follow-up of 32.2 months, the median progression-free survival (PFS) was 42.9 months; 1- and 3-year PFS rates were 93.9% and 68.8%, respectively. Median local control (LC) and overall survival (OS) were not reached, with 1- and 3-year LC rates of 98.5% and 84.6%, and OS rates of 98.5% and 88.7%, respectively. Toxicities were predominantly grade 1-2, with only one grade 3 pneumonitis. Larger ITV predicted poorer LC and PFS, whereas T stage independently predicted PFS and OS. Therefore, a non-uniform PTV strategy maintained clinical efficacy without compromising safety, supporting its application in UCNLC management.