Purpose
To investigate the factors that influence clinical outcomes after stereotactic body radiotherapy (SBRT) for non–small-cell lung cancer (NSCLC).
Methods and Materials
A total of 101 consecutive patients who underwent SBRT with 48 Gy in 4 fractions for histologically confirmed Stage I NSCLC were enrolled in this study. Factors including age, maximal tumor diameter, sex, performance status, operability, histology, and overall treatment time were evaluated with regard to local progression (LP), disease progression (DP), and overall survival (OS) using the Cox proportional hazards model. Prognostic models were built with recursive partitioning analysis.
Results
Three-year OS was 58.6 % with a median follow-up of 31.4 months. Cumulative incidence rates of LP and DP were 13.2 % and 40.8 % at 3 years, respectively. Multivariate analysis demonstrated that tumor diameter was a significant factor in all endpoints of LP, DP, and OS. Other significant factors were age in DP and sex in OS. Recursive partitioning analysis indicated a condition for good prognosis (Class I) as follows: female or T1a (tumor diameter ≤20 mm). When the remaining male patients with T1b–2a (>20 mm) were defined as Class II, 3-year LP, DP, and OS were 6.8 % , 23.6 % , and 69.9 % in recursive partitioning analysis Class I, respectively, whereas these values were 19.9 % , 58.3 % , and 47.1 % in Class II. The differences between the classes were statistically significant.
Conclusions
Tumor diameter and sex were the most significant factors in SBRT for NSCLC. T1a or female patients had good prognosis.
