Purpose/Objectives Stereotactic body radiation therapy (SBRT) has emerged as a standard treatment for early stage, medically inoperable lung cancer. Limited data evaluate radiation pneumonitis (RP) risk for SBRT following prior anatomic lung resection (ALR). We assess the incidence of RP and all pulmonary toxicity (PT) in patients treated with lung SBRT following ALR and compare to patients without prior ALR. Materials/Methods We reviewed the medical records of 84 consecutively treated patients with T1-T2b NSCLC treated with 88 courses of SBRT for 94 lung tumors from January 2007- December 2014, including 17 patients with prior ALR. Rates of RP and all PT were compared between patients with and without prior ALR. Results At 18.3 months median follow-up (range 1.8- 85.6 months), crude grade 2+ RP rates were 5.9% and 2.8% for patients with and without prior ALR, respectively (p=0.51), with 2-year estimates of freedom from RP of 89% and 97% (p=0.51). Crude rates of all grade 2+ pulmonary toxicity were 11.8% and 2.8% (p=0.11), respectively, with 2-year freedom from PT of 97% and 84%, (p=0.11). The 2 cohorts were well matched by mean lung dose, lung V20 (p=0.86) and prescribed dose (p=0.75). Two-year estimates of local control, cause-specific survival, and OS were similar between cohorts. Conclusions Observed rates of pulmonary toxicity were low among all patients, with a trend toward increased grade 2-3 lung toxicity among patients with prior ALR. Prior ALR did not increase risk of grade 4-5 RP, and SBRT appears safe and effective in this population.

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