Results of stereotactic body radiation therapy (SBRT) for T2 lung cancer: Outcomes of longer term follow-up.

Abstract

8542 Background: SBRT is a well-established, highly efficacious treatment for T1N0 non-small cell lung carcinoma (NSCLC). Its efficacy in T2N0 cancers is less clear. This is a review of our institutional experience with long-term follow-up. Methods: 45 patients with medically inoperable T2 N0/Nx M0 NSCLC who were treated with definitive SBRT between 2009 and 2013 were analyzed retrospectively. All patients underwent PET/CT staging and fiducial marker placement for image guided therapy with the Cyberknife platform. Radiation dose was 50 Gray in 5 fractions (N = 24), 50 Gray in 4 fractions (N = 11) or 54-60 Gray in 3 fractions (N = 10) delivered over 7 to 14 days. We analyzed overall survival from the date of start of SBRT, and we performed analyses actuarially using Cox regression analysis and Kaplan-Meier survival analysis for comparisons of hazard ratio (HR) among subgroups. Results: 45 patients were studied (median age 74). The 5-year actuarial overall survival was 18.7% (39.3% at 2 years), with most patients dying from lung cancer recurrence/progression outside of the treatment field. Subgroup analyses showed no statistically significant differences with respect to age, gender, histology, nominal radiation prescription dose, tumor diameter or PTV target volume (median PTV 87cc). There was statistically significantly better survival associated with increased maximum biologically effective dose (BED10) of radiation at the center of the tumor (p = 0.03). Conclusions: Unlike the outcomes for T1 NSCLC, our results in T2 NSCLC were disappointing, with a high rate of out-of-field failure and death from lung cancer. We stress the importance of diagnosis and treatment of NSCLC at the T1N0 stage. We suggest that patients with T2N0/Nx NSCLC be considered for SBRT dose intensification and/or combined modality therapy protocols.