Stereotactic body radiotherapy versus conventional radiotherapy for early-stage small cell lung cancer

This study was designed to compare survival outcomes for non-surgically managed T1-T2N0M0 small cell lung cancer (SCLC) who received either stereotactic body radiation therapy (SBRT) or conventionally fractionated radiotherapy (CFRT) using the National Cancer Data Base (NCDB).

The was queried between 2004-2015 for patients with T1-T2N0M0 SCLC. Patients must have been treated with curative intent SBRT or CFRT (delivered daily or twice daily, 45-70 Gy) with or without chemotherapy. The primary outcome was overall survival (OS). A subset analysis of patient receiving chemotherapy was also performed. A propensity score matched (PSM) analysis was performed to compare OS among patients who received chemotherapy.

We evaluated 1378 patients in the general cohort. Multivariable Cox regression analysis(MVA) in the general cohort revealed that SBRT was significantly associated with improved survival (HR 0.68, p<0.001) along with receipt of chemotherapy (HR 0.63, p <0.001). SBRT patients were less likely to receive chemotherapy compared to CFRT patients (p<0.01). In the chemotherapy subset, of 1096 patients, on MVA, there was a trend in favor of the SBRT group (HR 0.73; p=0.06). A 3:1 PSM analysis on the chemotherapy subset found similar results on MVA with a trend in favor of SBRT (p=0.06).

Patients with T1-2N0M0 SCLC treated with SBRT regimens incorporating chemotherapy had comparable outcomes to concurrent chemoradiotherapy using standard fractionation. Treatment paradigms for T1-2N0M0 SCLC incorporating SBRT warrant further exploration and should incorporate chemotherapy.