130: Stereotactic ablative radiotherapy (SABR) for early stage, medically inoperable non-small cell lung cancer (NSCLC): initial outcomes from 2 years' experience at the Oxford Cancer Centre, Oxford University Hospitals NHS Trust

Poster abstracts, 13th Annual British Thoracic Oncology Group Conference, 2015: Radiotherapy and implementing the technique in non-academic cancer centre in the UK. Methods: The decision to build a SABR programme was made in 2006 and the team attended Wurzburg SBRT and AVL Amsterdam IGRT courses. It was then registered as new technique with local NHS Trust’s clinical governance sub-committee and NICE. The patient selection, treatment planning, delivery, verification, quality assurance and data collection was carried out as per UK SBRT Consortium guidelines. Results: The total number of patients treated till December 2013 was 119. We selected first 95 patients with at least 6 months follow-up. Median age was 75 years (range: 48 91). 96% patients were deemed medically inoperable and 4% patients refused to have surgery. In 70% cases, it was T1 tumour followed by T2 (26%). Median tumour diameter was 2.2 cm (range: 1 4.6 cm). Histology was available in 63% of patients, adenocarcinoma being most common. PET scan was available in 93% of cases with median SUV of 9.8 (range: 1.6 30.7). Right upper lobe was most common geographical location (38%) followed by left upper lobe (28%) and left lower lobe (17%). The common dose fractionation regimes were; 55 Gy in 5 fractions (61%) 54 Gy in 3 fractions (30%) and 50 Gy in 10 fractions (5%). There were no grade 3/4 toxicities. There are only 3 local recurrences so far, though 14 patients developed distant metastases. Median overall survival is 38 months. Conclusion: SABR has become an accepted standard of care for medically inoperable early stage NSCLC, mainly based on results from large academic centres. Our series indicates that SABR can also be safely and effectively delivered in non-academic radiotherapy institutions. Disclosure: All authors have declared no conflicts of interest. 129 Stereotactic ablative body radiotherapy (SABR) for early stage non-small cell lung cancer (NSCLC) at a tertiary referral centre results of the first year of treatment at Birmingham R. Stevenson *, L. Price, G. Webster, M. Brennan, D. Stange, E. Wingate, K. Biard, Q. Ghafoor. Oncology, University Hospitals Birmingham NHS Trust, Birmingham, United Kingdom Introduction: SABR has a well-recognised role in the treatment of peripheral early stage NSCLC, with 3 year survival rates of over 70%; comparable to surgical series. It is currently unavailable in all UK centres. In May 2013, UHB established a SABR programme in accordance with UK SABR Consortium guidance. We describe our experience and outcomes of treating 31 patients in its first year. Methods: Patients eligible for SABR were selected via lung MDT. Between May 2013 and September 2014, prospective data was collected including patient demographics, tumour stage, histology, surgical contra-indications, pulmonary function, alternative treatment options and 3 or 9 month follow up. Results: Thirty-one patients have been treated with SABR since May 2013. Nine patients were initially identified as eligible for SABR, but did not receive treatment due to progression of co-morbid illness (n = 2), patient compliance issues (n = 5) and disease progression (n = 2). Without SABR, the majority of patients (19/31 61%) would have received best supportive care; the others radical radiotherapy with predicted 5 year survival of 10 30%. Three month follow up data was available for 20 patients, 1 achieving a complete response (CR), 14 partial response (PR) and 5 stable disease (SD). Nine month follow up was available for 10 patients, 1 achieving a CR, 5 PR, 2 SD and 2 progressive nodal disease. Treatment was well tolerated, the majority of patients experiencing no documented toxicity and others (n = 8) only grade 1 skin toxicity or pneumonitis documented. Conclusion: Our data illustrates the demographic profile of the initial 31 patients treated with SABR for early stage NSCLC at UHB. As expected the majority of patients selected were medically unfit for surgery. At present our data is too immature to draw conclusions

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regarding progression free and overall survival, but SABR appears to be a well tolerated treatment. Disclosure: All authors have declared no conflicts of interest. 130 Stereotactic ablative radiotherapy (SABR) for early stage, medically inoperable non-small cell lung cancer (NSCLC): initial outcomes from 2 years’ experience at the Oxford Cancer Centre, Oxford University Hospitals NHS Trust E. Hill1 *, G. Higgins2 , K. Vallis2 , R. Stuart1 , L. Drummond1 , A. Buckle1 , N. Panakis1 . 1 Oncology, Churchill Hospital, Oxford, United Kingdom, 2 Oncology, CRUK/MRC Oxford Institute for Radiation Oncology, Oxford, United Kingdom Introduction: SABR refers to the precise irradiation of an imagedefined extra-cranial lesion with the use of high radiation dose in a small number of fractions. This technique has become an internationally accepted standard treatment option for medically inoperable, peripheral, early stage NSCLC. A SABR programme was initiated at the Oxford Cancer Centre in December 2012. We conducted an audit of all patients treated with SABR in our centre to date, specifically to assess the criteria used for patient selection against UK SABR Consortium Guidelines 2014 and to evaluate early treatment outcomes. Methods: A prospective database was set up to monitor patients treated with SABR for NSCLC. Patients were followed up 4 weeks following completion of SABR and 3 monthly thereafter to assess toxicity. A CT scan was performed at 3 months then annually to assess response. Patient selection criteria were extracted from patient records retrospectively. Results: Twenty-nine patients with T1 3N0M0 tumours <5 cm were treated between December 2012 and September 2014. Eight patients had proven NSCLC (5 Squamous Cell Carcinomas, 2 Adenocarcinomas, 1 poorly differentiated Carcinoma); 20 tumours demonstrated growth and FDG-avidity on PET-CT. Twenty-three patients were medically inoperable. After a median follow-up of 3 months (range 1 19) no Grade 3 toxicities were observed. Of 16 patients evaluated with CT 3 months post SABR, there was no evidence of local tumour progression: 2 complete responses, 8 partial responses and 6 stable disease; 1 relapsed outside the treatment field (but had a partial response locally). One patient developed metastatic small cell lung cancer at 11 months post SABR having had no histological diagnosis pre-SABR. Conclusion: We have established a SABR service for patients with NSCLC selected in concordance with the UK SABR consortium guidelines. Early toxicity data is favourable but longer term followup data is required. Disclosure: All authors have declared no conflicts of interest. 131 Optimisation of stereotactic ablative body radiotherapy (SABR) planning: the Hull method N.S. Tambe *, W.P. Colley, A.K.E. Beaumont, A.W. Beavis. Radiation Physics, Hull and East Yorkshire Hospitals NHS Trust, Cottingham, United Kingdom Introduction: SABR is an optimal and attractive solution for peripheral, early stage, medically inoperable lung cancer. We implemented it in July 2014 following UK published guidelines [SABR UK Consortium, v.4.0, 2013]. Recently we improved our method of optimisation of these plans; we present our initial results. Methods: SABR patients were planned (Eclipse V11) using Rapid-Arc with two partial arcs. Initially, plans were optimised by considering PTV, ITV and OAR constraints; a Normal Tissue Objective (NTO) was used for all plans. To restrict the maximum dose within the ITV, plans were optimised such that 100% of the ITV received 110% of the prescription dose. This methodology resulted in high machine units (MUs), depending on tumour location. A retrospective study was performed to evaluate our planning technique. Ten plans were optimised using the MU objective, with maximum MUs set to 1800