Tumor Control and Toxicity for Common Stereotactic Body Radiation Therapy Dose-Fractionation Regimens in Stage I Non-Small Cell Lung Cancer

Abstract

To examine the impact of stereotactic body radiation therapy (SBRT) dose on outcomes in early-stage non-small cell lung cancer in a large single-institution series. We reviewed 600 patients treated from 2003 to 2012 for early-stage non-small cell lung cancer. The SBRT dose was at physician discretion on the basis of tumor size and location. Peripheral tumors were treated to 60Gy in 3 fractions (homogeneous planning), 48-50Gy in 4-5 fractions, or 30-34Gy in 1 fraction. Central tumors were treated to 50Gy in 5 fractions, 60Gy in 8 fractions, or 50Gy in 10 fractions. Patient, tumor, and treatment factors were assessed for their impact on patterns of failure, toxicity, and survival. An SBRT dose of 54-60Gy in 3 fractions was associated with a statistically significant lower rate of local failure (LF) (4.3% at 2years) compared with 30-34Gy in 1 fraction (21%), 48-50Gy in 4-5 fractions (15.5%), and 50-60Gy in 8-10 fractions (13.3%). Lower pre-SBRT hemoglobin and higher positron emission tomography standardized uptake value were also associated with LF. Nodal failure, distant failure, and overall survival were similar between fractionation groups. Pulmonary toxicity (crude rate, any grade) was slightly higher for 3 fractions (5.0%) compared with 1 (3.2%) or 4-5 fractions (3.8%). Chest wall toxicity was also higher for 3 (23.7%) compared with 1 (8.6%) or 4-5 (7.7%) fraction regimens. Although higher biologically equivalent dose SBRT (150-180 Gy10) may be associated with slightly lower LF, it was also associated with mildly increased toxicity and no difference in other patterns of failure or overall survival.