Temporal Trends in the Utilization of Stereotactic Body Radiotherapy for Non-Small Cell Lung Cancer in the United States

Abstract

The optimal treatment of early stage non-small cell lung cancer (NSCLC) continues to evolve. Stereotactic body radiation therapy (SBRT) has become the preferred treatment modality for patients deemed medically inoperable. The trends in SBRT utilization and other treatment modalities were evaluated over time for patients with early stage NSCLC. We hypothesize that an increase in the use of SBRT for early NSCLC may be related to the increase in smaller lesion size detected in recent years. The National Cancer Database was queried for patients at least 18 years of age with pathologically proven, cT1-T3N0 and less than 5 cm in size (AJCC 7th ed.), NSCLC from 2004-2014. Patients who got chemotherapy or radiation before surgery were excluded. Patients were grouped by treatment modality (sublobar resection, lobectomy, SBRT, and no treatment). Treatment modality as a percentage of total new cases was assessed by year of diagnosis and by tumor size. A multinomial logistic regression model was used to measure the relationship between treatment modality, year of diagnosis, and tumor size, after controlling for other covariates. A total of 156,092 patients met inclusion criteria and were included in the analysis. The absolute number of cases of lobectomy and sublobar resections remained stable over 2008-2014, while SBRT cases rose over the course of the study period. The proportion of lobectomy cases decreased from 56% in 2008 to a nadir of 44% in 2014. Proportion of SBRT use increased from 1.5% to 25%, and the proportion of patients receiving no therapy declined from 27% to 13%. Mean lesion size decreased from 24.5 ± 10.8 mm (mean ± SD) to 22.5 ± 10.1 mm over the study period. In the multinomial logistic regression model, the likelihood of receiving SBRT continuously increased each year while no treatment decreased over the study period (p<0.0001) after controlling for tumor size, age, race, insurance, facility type, Charlson-Deyo score, and education. SBRT was also more likely to be used for smaller tumors compared to lobectomy (p<0.0001). Utilization of SBRT for early stage NSCLC increased significantly over the study period. Given the lack of significant change in the number of surgeries, much of the SBRT use appears to have focused on patients who would have otherwise received no therapy. The lesion size treated with SBRT decreased slightly over time, in parallel with the overall population, likely due to combination of increased incidental findings from imaging and screening efforts. This study provides important information on patterns of care for early stage NSCLC in the U.S. and identifies SBRT as an important treatment modality, especially for small tumors and for poor surgical candidates who may otherwise receive no treatment.