Stereotactic Body Radiation Therapy for Early-Stage Non-Small-Cell Lung Carcinoma: Four-Year Results of a Prospective Phase II Study

Purpose: The 50-month results of a prospective Phase II trial of stereotactic body radiation therapy (SBRT) in medically inoperable patients are reported. Methods and Materials: A total of 70 medically inoperable patients had clinically staged T1 (34 patients) or T2 (36 patients) (≤7 cm), N0, M0, biopsy-confirmed non-small-cell lung carcinoma (NSCLC) and received SBRT as per our previously published reports. The SBRT treatment dose of 60-66 Gy was prescribed to the 80% isodose volume in three fractions. Results: Median follow-up was 50.2 months (range, 1.4-64.8 months). Kaplan-Meier local control at 3 years was 88.1%. Regional (nodal) and distant recurrence occurred in 6 (8.6%) and 9 (12.9%) patients, respectively. Median survival (MS) was 32.4 months and 3-year overall survival (OS) was 42.7% (95% confidence interval [95% CI], 31.1-54.3%). Cancer-specific survival at 3 years was 81.7% (95% CI, 70.0-93.4%). For patients with T1 tumors, MS was 38.7 months (95% CI, 25.3-50.2) and for T2 tumors MS was 24.5 months (95% CI, 18.5-37.4) (p = 0.194). Tumor volume (≤5 cc, 5-10 cc, 10-20 cc, >20 cc) did not significantly impact survival: MS was 36.9 months (95% CI, 18.1-42.9), 34.0 (95% CI, 16.9-57.1), 32.8 (95% CI, 21.3-57.8), and 21.4 months (95% CI, 17.8-41.6), respectively (p = 0.712). There was no significant survival difference between patients with peripheral vs. central tumors (MS 33.2 vs. 24.4 months, p = 0.697). Grade 3 to 5 toxicity occurred in 5 of 48 patients with peripheral lung tumors (10.4%) and in 6 of 22 patients (27.3%) with central tumors (Fisher's exact test, p = 0.088). Conclusion: Based on our study results, use of SBRT results in high rates of local control in medically inoperable patients with Stage I NSCLC.