P2.16-16 SABRTOOTH: A Fasibility Study of SABR Versus Surgery in Patients with Peripheral Stage I NSCLC Considered to Be at Higher Risk for Surgery

Stage I NSCLC is curable by surgery and Stereotactic Ablative Radiotherapy (SABR). Many patients have co-morbidities that place them at higher risk of surgical complications. For such patients it is unknown whether the potential benefits of surgery are outweighed by the risks since published randomised trials comparing surgery with SABR have been underpowered. The SABRTooth study was designed to determine the feasibility of randomising patients between the two treatments and thus performing a larger RCT. Four thoracic oncology centres and a referral site participated. Patients with peripheral (>2cm from the main airways) stage T1-T2bN0M0 NSCLC were considered for study entry. Patients at higher risk were identified using several criteria including Thoracoscore and the Nottingham Risk Score and confirmed by multidisciplinary team consensus. Eligible patients were approached by a respiratory physician and research nurse, consented and randomised (1:1) before consulting a surgeon or oncologist. Surgery was preferably by lobectomy with lymph node sampling/resection although sub-lobar resection was permitted. SABR was delivered as per the UK SABR guidelines. An average recruitment rate of 3 patients/month from the 5 centres over a formal monitoring period was set to prove feasibility of a larger RCT. Meetings with the trial sites and patient representatives were held through-out to improve recruitment. Qualitative research was embedded into the study with interviews for patients who declined participation or randomised treatment. Between July 2015-January 2017 318 patients were assessed for eligibility of which 106 were initially considered eligible. 84 patients were approached for the study and 24 (29%) were randomised (10 surgery, 14 SABR); a mean recruitment rate of 1.7 per month. The median age was 75 (range 54-88). The main reason for declining the study was patient preference with 29% preferring surgery and 42% SABR. Overall 9/24 (38%) did not receive their randomised treatment. Of 7 patients randomised to surgery, 6 received SABR, 1 radical radiotherapy and of 2 patients randomised to SABR, 1 received radical radiotherapy, 1 was lost to follow-up. Despite recruiting at higher rate/centre than previous SABR versus surgery trials, the SABRTooth study failed to meet its recruitment target and the majority of patients randomised to surgery subsequently underwent SABR. Therefore, conducting a large RCT in the UK was shown not to be feasible. However, establishing which patients should have surgery or SABR for early stage NSCLC remains a critical question and alternative study designs are being developed to provide an answer for patients and clinicians.