Stereotactic body radiation therapy versus conventionally fractionated radiation therapy for early stage non-small cell lung cancer

Purpose: To date, no published randomized trials have shown stereotactic body radiation therapy (SBRT) to offer superior outcomes to conventionally fractionated radiation therapy (CFRT) for early-stage non-small cell lung cancer (NSCLC). The largest study to date, this investigation of a contemporary national database sought to evaluate practice patterns and survival between CFRT and SBRT.

Methods: The National Cancer Database was queried (2004-2015) for histologically-confirmed cT1-2aN0M0 NSCLC undergoing definitive CFRT or SBRT. Multivariable logistic regression ascertained factors associated with SBRT administration. Kaplan-Meier analysis evaluated overall survival (OS) before and following propensity matching. Cox proportional hazards modeling determined variables associated with OS.

Results: Of 23,088 patients, 2286 (10%) patients received CFRT and 20,802 (90%) SBRT. SBRT was less often delivered in African-Americans, patients with lower incomes, urban location, greater comorbidities, at non-academic centers, in larger tumors, and squamous histology (p < 0.05 for all). Patients treated with SBRT had a higher median OS (38.8 months vs. 28.1 months, p < 0.001). At median follow-up of 44.6 months, the median OS for the SBRT group was 38.8 months, versus 28.1 months for CFRT (p < 0.001). These findings persisted following propensity matching. Subgroup analyses demonstrated improved OS in multiple subcohorts (T2, Charlson comorbidity score 2-3, squamous histology). SBRT was also independently associated with OS on Cox multivariate analysis (p < 0.001).

Conclusions: The largest such study to date (comprising of over 23,000 patients), this investigation demonstrates the survival benefit to ablative radiotherapy for early-stage NSCLC. Maturation of comparative prospective trials is eagerly awaited.