Risk‐adapted stereotactic body radiation therapy for central and ultra‐central early‐stage inoperable non‐small cell lung cancer

To determine the therapeutic efficacy and safety of risk‐adapted stereotactic body radiation therapy (SBRT) schedules for patients with early‐stage central and ultra‐central inoperable non‐small cell lung cancer. From 2006 to 2015, 80 inoperable T1‐2N0M0 NSCLC patients were treated with two median dose levels: 60 Gy in six fractions (range, 48‐60 Gy in 4‐8 fractions) prescribed to the 74% isodose line (range, 58%‐79%) for central lesions (ie within 2 cm of, but not abutting, the proximal bronchial tree; n = 43), and 56 Gy in seven fractions (range, 48‐60 Gy in 5‐10 fractions) prescribed to the 74% isodose line (range, 60%‐80%) for ultra‐central lesions (ie abutting the proximal bronchial tree; n = 37) on consecutive days. Primary endpoint was overall survival (OS); secondary endpoints included progression‐free survival (PFS), tumor local control rate (LC), and toxicity. Median OS and PFS were 64.47 and 32.10 months (respectively) for ultra‐central patients, and not reached for central patients. Median time to local failure, regional failure, and any distant failures for central versus ultra‐central lesions were: 27.37 versus 26.07 months, 20.90 versus 12.53 months, and 20.85 versus 15.53 months, respectively, all P < .05. Multivariate analyses showed that tumor categorization (ultra‐central) and planning target volume ≥52.76 mL were poor prognostic factors of OS, PFS, and LC, respectively (all P < .05). There was one grade 5 toxicity; all other toxicities were grade 1‐2. Our results showed that ultra‐central tumors have a poor OS, PFS, and LC compared with central patients because of the use of risk‐adapted SBRT schedules that allow for equal and favorable toxicity profiles.