Factors Associated with Radiation Toxicity and Survival in Patients with Presumed Early-Stage Non-Small Cell Lung Cancer Receiving Empiric Stereotactic Ablative Radiotherapy.

OBJECTIVES: Stereotactic ablative radiotherapy (SABR) has become the standard of care for inoperable early-stage non-small cell lung cancer (NSCLC). Many patients cannot safely undergo a biopsy because of poor pulmonary function and are empirically treated with radiotherapy. This study aimed to evaluate factors associated with radiation toxicity in patients receiving empiric SABR.
METHODS: We performed a retrospective review of 69 patients. Patients and tumor characteristics, radiation doses, pulmonary function tests, and toxicity (acute ≤ 90 days and late > 90 days) were analyzed to find associations with overall survival on Kaplan-Meier curves and differences in patient populations with χ2 and Mann-Whitney U tests.
RESULTS: Median age was 71 years. Tumors were classified as peripheral in 62 patients (89.9%). After a median follow-up of 18 months, 39 patients (56.5%) were alive with 4 local recurrences (5.7%), 10 regional failures (14.3%), and 15 distant metastases (21.4%). Nineteen of 67 (26.3%) patients had acute toxicity of which 9 had acute grade ≥ 2 toxicity. There were differences in overall survival based on operability status (P = .031) and acute toxicity (P < .001). Pretreatment oxygen dependence (P = .003), central location (P < .001), and new oxygen requirement (P = .02) were significantly associated with acute grade ≥ 2 toxicity. No association was found with performance on pulmonary function tests.
CONCLUSION: Empiric SABR in presumed early-stage NSCLC appears to be safe and may increase overall survival. Acute grade ≥ 2 toxicity was significantly associated with pretreatment oxygen dependence, central location, and new oxygen requirement. No association was found with poor pulmonary function.