Stereotactic Body Radiation Therapy for Central Early-Stage NSCLC: Results of a Prospective Phase I/II Trial

Introduction: We report results from a prospective phase I/II trial for patients with centrally located, early-stage NSCLC receiving stereotactic body radiation therapy. Methods: Eligible patients were medically inoperable with biopsy-proven NSCLC within 2 cm of the proximal bronchial tree or 5 mm of the mediastinal pleura or parietal pericardium. Phase I had four dose levels using 5 fractions: 9, 10, 11, and 12 Gy per fraction. The primary phase II objective was to determine if the maximum tolerated dose in phase I achieved local control greater than 80% at 2 years. Results: Seventy-four patients were enrolled; 23 to phase I and 51 to phase II. Two phase I patients treated with 10 Gy × 5 fractions developed unrelated acute grade 3 lung toxicities which resolved. The phase II dose level selected was 11 Gy × 5 fractions. The median follow-up for living phase II patients was 27 months (range, 9 to 58 months). Two-year local control using 11 Gy × 5 fractions was 85% (95% confidence interval [CI]: 62%–95%). Two-year overall survival was 43% (95% CI: 28%–57%). Three patients (6%, 95% CI: 1%–17%) experienced acute grade 3 and 4 cardiac or pulmonary toxicities. Of the 41 patients evaluable for late cardiac and pulmonary toxicity, 11 (27%, 95% CI: 14%–43%) developed grade 3, 5 (12%, 95% CI: 4%–26%) developed grade 4, and 1 (4%, 95% CI: 0%–13%) died of grade 5 toxicity. Conclusion: Stereotactic body radiation therapy for central NSCLC using 11 Gy × 5 fractions is tolerable and has excellent local control, but is associated severe late toxicity in some patients.