Stereotactic body radiotherapy for central lung tumors: Finding the balance between safety and efficacy in the “no fly” zone

BACKGROUND: Stereotactic body radiotherapy (SBRT) has emerged as a highly effective technique to treat medically inoperable non‐small cell lung cancer (NSCLC). Doses must be chosen carefully when treating central lesions because of the potential for significant toxicity. This study reviews the outcomes of a cohort of patients with central lung tumors treated with SBRT. METHODS: We identified 18 patients (12 women, 6 men) with central lesions that were treated with SBRT at our institution. Overall survival and local, regional, and distant control rates were assessed by Kaplan–Meier methodology. Correlations with outcomes were determined by multivariate analysis via Cox regression models. RESULTS: Eighty‐nine percent of patients had a pathological diagnosis of NSCLC. The median dose to the planning target volume was 40 Gy (range: 30–50) in five fractions, yielding a median biologic equivalent dose (BED(10)) of 72 (range: 48–100). The median planning target volume was 34 cc (range: 13.3–89). Local control was 87% at one year. Median overall survival was 45 months, with a two‐year rate of 61%. The two‐year regional control rate was 87%. BED(10) > 72 predicted improved progression‐free survival, with one‐year rates of 100% versus 40% with increased BED (P = 0.012). No grade 3 or higher acute or late toxicity was observed. CONCLUSIONS: Lung SBRT to central lesions is safe and effective when using five fraction regimens. BED(10) < 72 predicted disease progression, highlighting the importance of choosing an effective dose fractionation scheme, which must in turn be balanced with potential toxicity.