Adjuvant Systemic Therapy in Patients With Early-Stage NSCLC Treated With Stereotactic Body Radiation Therapy

Stereotactic body radiation therapy (SBRT) is commonly used to treat nonsurgical patients with early-stage NSCLC. There are no prospective data on the role of adjuvant chemotherapy in this setting.

Patients (≥18 years) diagnosed with clinical stages I-II NSCLC from 2004 to 2013 were identified using the National Cancer Database (n = 11,836). The Kaplan-Meier method was used to estimate overall survival (OS) distributions and the log-rank test was used to compare distributions by treatment strategy. Clinical stages I and II were subdivided according to the TNM staging and log-rank tests was used to compare survival distributions by treatment strategy within each subgroup.

In patients with T2bN0, median OS in the SBRT alone and SBRT plus adjuvant chemotherapy groups were 16.5 months versus 24.2 months, respectively (95% confidence interval [CI]: 14.1-20.1 months and 18.8-33.3 months, respectively; p < .001); whereas for T3N0, median OS times were 13 months and 20.1 months, respectively (95% CI: 11.7-14.5 mohths and 17.7-21.9 months, respectively; p < .001). For tumors 4 cm or larger and node-negative disease, median OS was 15.9 months in the SBRT-alone group, and 19 months in the SBRT-plus-chemotherapy group (95% CI: 15.1-16.8 months and 17.9-20.8 months, respectively; p < .001). For patients with tumors less than 4 cm and node-negative disease, the median OS was 28.5 months in the SBRT-alone group and 24.3 months in the SBRT-plus-chemotherapy group (95% CI: 27.4-29.4 months and 22.8-26.1 months, respectively; p < .001).

SBRT followed by adjuvant chemotherapy was associated with improved OS in comparison with SBRT alone in patients with T greater than or equal to 4 cm, similar to that seen after surgery.