Role of Stereotactic Body Radiotherapy for Early-Stage Non-Small Cell Lung Cancer in Borderline Patients for Surgery due to Impaired Pulmonary Function

Abstract

Stereotactic body radiotherapy (SBRT) is recommended only for inoperable patients with early stage (e-stage) non-small cell lung cancer (NSCLC). We compared outcomes between surgery and SBRT in borderline patients for surgery due to impaired pulmonary function (PF).In our institution, operable patients (i.e., sufficient PF and no serious comorbidity) were generally selected for surgery after discussion among the multidisciplinary team. The inoperable patients decided after discussion among the multidisciplinary team and those who refused surgery were usually selected for SBRT. The total dose of 44 or 48 Gy for tumors with a maximum diameter < 1.5 cm, 48 or 50 Gy for tumors of 1.5-3 cm, and 52 Gy for tumors > 3 cm was prescribed to the isocenter of the planning target volume. Surgery included lobectomy, sub lobar resection (SLR), and wedge resection (WR) by video-assisted thoracic surgery or open thoracotomy at the thoracic surgeons' discretion. We reviewed single-institutional retrospective data of 578 patients with clinically T1-2N0M0 NSCLC treated by surgery or SBRT between 2004 and 2014, and extracted a cohort with borderline impaired PF for surgery, which was defined as predicted postoperative (PPO) forced expiratory volume in 1 second (FEV1) of < 50% and ≥ 30%. Overall survival (OS), cancer-specific survival (CSS), and disease-free survival (DFS) were compared between surgery and SBRT using propensity score-matching (PSM) to avoid bias.Among a total of 116 eligible patients with a median PPO FEV1 of 45%, PSM identified 25 patients from each group with similar characteristics. After PSM, 17 (68%), 3 (12%), and 5 (20%) patients underwent lobectomy, SLR, and WR, respectively. The median age, pretreatment FEV1, and follow-up durations for the surgery and SBRT groups were 75 and 74 years, 58% and 56%, and 56 and 60 months, respectively. The 5-year OS, CSS, and DFS rates of the surgery vs SBRT groups were 60% vs 63%, 76% vs 81%, and 52% vs 48%, respectively (P = 0.97, 0.81, and 0.99). Among the matched patients, one patient died of massive hemorrhage during lobectomy. The 90-day surgical mortality was 4.0% (1 of 25), but no treatment-related death was observed after SBRT. In the surgery group after PSM, 10 (40%) patients had grade 2 or greater adverse events. In the SBRT group after PSM, 5 (20%) patients had treatment-related grade 2 or greater adverse events. After PSM, the incidence of grade 2 or greater adverse events in the surgery group was twice as high as that in the SBRT group, but this difference was not significant by the χ2 test (40% vs 20%, P = 0.22).Although surgery and SBRT had similar survivals, fewer adverse events were observed after SBRT. Our current study suggests that SBRT is a reasonable option for impaired PF patients borderline for surgery in e-stage NSCLC. However, a prospective study of this specific population is warranted in order to improve patient selection for SBRT or surgery.