Trends in stereotactic body radiation therapy for stage I small cell lung cancer

We aimed to report trends in stereotactic body radiation therapy (SBRT) utilization, dose prescriptions, and chemotherapy administration for stage I small cell lung cancer (SCLC) in the United States.

The National Cancer Data Base (NCDB) was used to identify patients with cT1-2 N0 SCLC treated with SBRT between 2004 and 2013. Trends in SBRT use and dose prescription were analyzed over time. Multivariable logistic regression was used to determine factors associated with the administration of chemotherapy with SBRT. The Kaplan-Meier method was used to estimate overall survival.

Of 9265 patients with clinical stage I SCLC who were examined for initial treatment allocation, 285 were treated with SBRT and represented the subject of the primary analysis. SBRT utilization increased from 2004 (0.4% of all stage I patients diagnosed that year) to 2013 (6.4%). During this same time period, definitive surgical management also increased from 14.9% of all patients in 2004 to 28.5% in 2013. The median SBRT biologically effective dose (BED₁₀) was 112.5Gy (range, 72-290) and only 33 out of 285 (11.6%) received a BED₁₀<100Gy. Nearly half of all patients (130/285, 45.6%) received chemotherapy, with 42.7% of those patients receiving their chemotherapy prior to SBRT. On multivariable logistic regression, only age<75 (the median) vs. ≥75years (OR 4.97, 95% CI 2.96-8.35, p<0.001) and year of diagnosis 2004-2008 vs. 2009-2013 (OR 2.58, 95% CI 1.27-5.26, p=0.009) were predictive of chemotherapy use with SBRT. After median follow up of 45 months, the median survival was 23.5 months.

Our findings suggest that SBRT utilization for stage I SCLC has increased between 2004 and 2013, highlighting the need for additional research to validate the feasibility of this management approach for inoperable patients.