Stereotactic Body Radiotherapy and Precision Hypofractionated Radiotherapy versus Surgery for Stage I Non-Small Cell Lung Cancers: An 11-year review of a Provincial Cancer Registry

Surgery is currently the standard management for resectable stage I non-small cell lung cancers (NSCLC). Stereotactic body radiotherapy (SBRT) and precision hypofractionated radiotherapy (hypoRT) have shown promising outcomes. Large randomized trials comparing the modalities have yet to be completed. The objective of this study is to compare the provincial outcomes of patients treated with SBRT/hypoRT to those treated with surgery. We conducted a retrospective analysis of all provincial patients with stage I NSCLC who underwent surgery or SBRT/hypoRT (biological equivalent dose of at least 84 Gy), from 2006 to 2016. Baseline patient, tumor, treatment and clinical outcome data were collected from the British Columbia Cancer Registry. Overall survival (OS) and cancer specific survival (CSS) were analyzed using Kaplan-Meier method. We further analyzed patients based on age, with 75 as cut off for older population. Cox regression analysis was performed to identify predictors of outcomes. Among 1230 patients, 235 (19.1%) were treated with SBRT/hypoRT and 995 (80.9%) with surgery. 158 (12.2%) patients received 48Gy in 4Fx, 42 (3.4%) 60Gy in 8Fx, 35 (2.8%) 60Gy in 15Fx. 783 (63.7%) patients underwent lobectomy, 28 (2.3%) pneumonectomy, 184 (15.0%) sub-lobar resection. The median age was 69, with 339 (27.6%) age >75. The median follow-up was 26.2 months for SBRT/hypoRT and 29.4 months for surgery. The 2- and 5-year OS were 73.8% and 27.7% for SBRT/hypoRT, and 78.4% and 36.1% for surgery, with no significant difference between the groups (p=0.182). Differences in OS were not significant among the radiotherapy dose fractionations (p=0.653) or the surgery types (p=0.193). Comparing SBRT/hypoRT to surgery, significant differences in OS were not detected for patients age <75 (p=0.299) nor >75 (p=0.224). The 2- and 5-year CSS were respectively 85.2% and 54.3% for SBRT/hypoRT, and 81.1% and 42.2% for surgery, with improved outcomes in the SBRT/hypoRT group (p=0.004). Patients age >75 had greater CSS with SBRT/hypoRT (p<0.001), with no significant difference in patients age <75 (p=0.077). On multivariate analysis, there was no significant indicator of improved OS found for the SBRT/hypoRT group. For the surgery group, age <75 (p<0.001) predicted for better OS while ECOG (ref=0) 2 (p=0.041), 3 (p<0.001), 4 (p<0.001) predicted for worse. At a registry level, SBRT/hypoRT achieves OS outcomes similar to surgery. Improved CSS is observed in the SBRT/hypoRT cohort, notably for patients age >75. Further evaluation in large randomized studies is warranted.