Stereotactic body radiation therapy for early stage non-small cell lung cancer: Results of a prospective trial

Patients affected with early stage (IA-IB) non-small cell lung cancer (NSCLC), deemed medically inoperable, are usually treated by conventional 3D-CRT, with poor results in terms of local tumour control and survival. Hypofractionated stereotactic body radiation therapy (SBRT) appears to be a valid alternative option, with high rates of local control and promising survival rates according to recent reported series. We herein report the final results of a prospective phase II trial of SBRT in 62 stage I NSCLC patients, homogeneously treated with three fractions of 15Gy each, given every other day during a 1 week time, up to a total dose of 45Gy; dose was prescribed to the 80%-isodose encompassing planning target volume. Patients were immobilized in a dedicated stereotactic body frame; margins around gross tumour volume were 5mm in the axial plane and 10mm in the longitudinal direction. Median age was 73.7 years. A pathologic confirmation of NSCLC was obtained in 64.5% of patients. Forty-three patients had stage IA and 19 stage IB disease. The majority of patients did not experience any toxicity; mild skin reactions, fatigue, dyspnea/cough or transient thoracic pain were recorded in approximately 10% of patients. With a median follow-up time of 28 months, 2 patients experienced an isolated local relapse, 4 an isolated nodal relapse and 15 a systemic failure. At 3 years, local control rate was 87.8%, cancer-specific survival 72.5%, overall survival 57.1%, with 8 out of 20 non-cancer related deaths. In multivariate analysis, tumour volume was associated with a better outcome. In our series, SBRT was well tolerated and confirmed its efficacy, with local control and survival rates globally superior to those reported using conventional radiotherapy. A longer follow-up is needed in order to establish a correct comparison with surgical series, and to fully ascertain a potential negative impact of SBRT on comorbidities of such a fragile patients population.