Stereotactic radiotherapy of histologically proven inoperable stage I non-small cell lung cancer: patterns of failure.

Background And Purpose: To report patterns of failure of stereotactic body radiation therapy (SBRT) in inoperable patients with histologically confirmed stage I NSCLC.

Materials And Methods: Ninety-two inoperable patients (median age: 75 years) with clinically staged, histologically proven T1 (n=31) or T2 (n=61), N0, M0 non-small cell lung cancer (NSCLC) were included in this study. Treatment consisted of 3-5 fractions with 7-15 Gy per fraction prescribed to the 60% isodose.

Results: Freedom from local recurrence at 1, 3 and 5 years was 89%, 83% and 83%, respectively. All 10 local failures were observed in patients with T2 tumors. Isolated regional recurrence was observed in 7.6%. The crude rate of distant progression was 20.7%. Overall survival at 1, 3, and 5 years was 79%, 38% and 17% with a median survival of 29 months. Disease specific survival at 1, 3, and 5 years was 93%, 64% and 48%. Karnofsky performance status, T stage, gross tumor volume and tumor location had no significant impact on overall and disease specific survival. SBRT was generally well tolerated and all patients completed therapy as planned.

Conclusion: SBRT for stage I lung cancer is very well tolerated in this patient cohort with significant cardiopulmonal comorbidity and results in excellent local control rates, although a considerable portion develops regional and distant metastases.