Updated Results Of Propensity-Based Analysis Of Stereotactic Body Radiation Therapy And Sublobar Resection For Stage I Non-Small Cell Lung Cancer In Patients At High Risk For Lobectomy

We previously reported survival comparison between stereotactic body radiotherapy (SBRT) and sublobar resection (SLR) for stage I non-small cell lung cancer (NSCLC) in patients at high risk for lobectomy (Eur J Cancer. 2014;50:2932). The previous study performed propensity score match (PSM) without body mass index (BMI) taken into consideration, and revealed that SBRT was comparable to SLR in lung cancer death, but not in non-lung cancer death. Purposes of the present study are to update results of the previous report based on longer follow-up, and to compare survival outcomes between SBRT and SLR under PSM that incorporates BMI. The patient cohort consisted of 115 and 65 patients who underwent SBRT and SLR, respectively, for clinical stage I NSCLC because of medical comorbidity between January 2003 and December 2009. The prescribed dose was 48 Gy in 4 fractions to the isocenter for most SBRT patients. PSM was performed based on age, gender, performance status (PS), tumor diameter, histology, forced expiratory volume in 1 second (FEV1), Charlson comorbidity index (CCI), and BMI. Median potential follow-up periods extended to 8.0 and 7.9 years for SBRT and SLR patients, respectively. The SBRT patients were elderly, poorer in PS, lower in FEV1, higher in CCI, and larger in tumor diameter than those with SLR, as previously reported. BMI tended to be lower in SBRT. Underweight, normal range and overweight according to WHO classification of BMI were observed in 18%, 64% and 18% of the SBRT group, respectively. Those were 6%, 68%, and 26% in SLR. Before the PSM, overall survival (OS) was significantly different between the two groups (40.3% and 62.6% at 5 years for SBRT and SLR, respectively, P<0.01).The PSM picked up 46 patients for each treatment group. Patient characteristics were well balanced between the groups. After the PSM, SBRT showed similar OS to SLR (48.4% and 53.7% at 5 years for SBRT and SLR, respectively; P = 0.68). Furthermore, cumulative incidence was comparable not only for lung cancer death, but for non-lung cancer death, between SBRT and SLR (35.5% and 30.7% for lung cancer death at 5 years; P = 0.42, and 15.7% and 15.6% for non-lung cancer death; P = 0.52, respectively). Regarding patterns of failure, cumulative incidence of local recurrence was higher in SBRT than SLR (33.8% and 15.6%; P = 0.07). Regional or distant recurrence was not different between SBRT and SLR. The present study confirmed that SBRT can be an alternative treatment to SLR for patients at high risk for lobectomy.