ESTRO 36 Abstract Book

S354 ESTRO 36 _______________________________________________________________________________________________

equivalent dose (BED), fractionation schedule of SBRT, size of largest metastasis, development of local recurrence after SBRT, delay in initiation of SBRT for ≥ 4 months, presence of comorbidity, location of lung metastasis: central versus peripheral and location of metastasis in lower lobes versus other locations. Primary tumors included 117 colorectal tumors, 36 lung cancers, 11 melanoma, 10 sarcoma, 7 breast carcinoma and 25 tumors were from other sites. Median follow up was 23 months (range 1-100). Results Median survival in the entire cohort was 32 months. The 2, 3, and 5 year OS rate was 63%, 47%, and 30%, respectively. On univariate analysis, synchronous metastasis and colorectal primary site were significantly associated with improved OS. On multivariate analysis, presence of synchronous metastasis was the only factor independently associated with better OS, adjusted HR=0.57 (95% CI 0.36-0.89). On further categorization, there was significant difference (p =0.048) among synchronous liver metastasis that later developed pulmonary oligorecurrence (median OS 63 months), synchronous pulmonary oligometastasis (Median OS 40 months) and metachronous pulmonary oligometastasis (Median OS 29 months).Local control for the entire group was at 2, 3, and 5 year was 83%, 79% and 73%, respectively. Less than 2% of patients experienced grade 3 acute or late toxicities. Conclusion SBRT to pulmonary oligometastasis resulted in a 5 year survival of 30%. Synchronous metastases were independently associated with better OS.

A total of 73 lesions were treated in 68 patients between Feb 2013 and Feb 2016. Median follow-up amounted to 11 months (2-28 months). Histology was available in 64% of patients, of which 66% were adenocarcinomas and 30% squamous cell carcinomas. Delivered dose schedules were 48Gy/4 fractions (n= 59), 51Gy/3 fractions (n= 9), 60Gy/8 fractions (n= 5). In 12% of lesions DTT was used. Reasons for omitting DTT were: poor baseline pulmonary function (n=7), deep location not allowing visicoil insertion (n=3), presence of a visicoil in the other lung (n=1) and history of prior pneumothorax (n=1). Mean treatment time for a DTT session was 28.6 minutes, comparable with the mean ITV treatment time (29.5min). Use of DTT resulted in an average PTV reduction of 32% (10-48%) compared to corresponding ITV plans (p=0.004). Two patients needed a temporary chest tube for a small pneumothorax after marker implantation, but no radiotherapy toxicity was observed in the patients treated with DTT. In the ITV group, only 1 patient experienced a grade 2 radiation pneumonitis and 2 patients presented with a COPD exacerbation in the weeks following RT. In DTT lesions, our results also demonstrated a significant variability in respiration-induced tumor motion: mean craniocaudal motion measured on 4DCT was 13.1mm ± 3.5mm, while during treatment delivery a mean maximum value of 18.9mm ± 8.0mm was observed (p=0.04). One-year Kaplan-Meier outcome analysis shows a local control of 97%, a progression-free survival of 84% and an overall survival of 91%, with no differences between the DTT and ITV groups. Conclusion Vero SBRT demonstrated excellent outcomes and limited toxicity in early stage lung cancer. Compared to ITV, DTT offered a smaller irradiated volume and allowed adaption to intrafraction movements not covered by 4DCT. DTT by use of a single marker is feasible in primary lung cancer patients, but the need for an implanted marker limits applicability in this population. PO-0678 Health-related quality of life reporting in lung cancer trials: A methodological appraisal. L. Van der Weijst 1 , V. Surmont 2 , W. Schrauwen 3 , Y. Lievens 4 1 Ghent University Hospital, Radiation Oncology and Experimental Cancer Research, Gent, Belgium 2 Ghent University Hospital, Pneumology, Gent, Belgium 3 Ghent University Hospital, Medical Psychology, Gent, Belgium 4 Ghent University Hospital, Radation Oncology and Experimental Cancer Research, Ghent, Belgium Purpose or Objective Health-related quality of life (HRQoL) is an important outcome measurement in locally-advanced non-small cell lung cancer (LA-NSCLC) patients, often presenting considerable comorbidities, hence in clinical trials assessing the role of radiotherapy in this patient population. In addition to the correct execution of these HRQoL studies, it is equally important that the HRQoL data, retrieved from these clinical trials, are reported in a standardized manner, as to draw correct conclusions to support treatment decisions. The aim of this study is to examine the methodological quality of HRQoL reporting in a series of studies retrieved through a systematic review of the literature. Material and Methods A literature search was performed in PubMed, Embase and Web of Science, with the following inclusion criteria: English language, clinical trial, LA-NSCLC patient population, HRQoL assessment, full-text availability and published between 2005 – 2015. The methodological quality of each study was assessed by the standard checklist for the quality of HRQoL reporting in cancer clinical trials [Efficace et al. J Clin Oncol 2003;21:3502-

PO-0677 Vero SBRT for early stage lung cancer: a phase II trial with dynamic tracking in selected lesions C. Collen 1 , R. Van den Begin 1 , M. Boussaer 1 , B. Engels 1 , J. Dhont 1 , M. Burghelea 1 , G. Storme 1 , M. De Ridder 1 1 Universitair Ziekenhuis Brussel, Department of Radiation Oncology, Brussels, Belgium Purpose or Objective To evaluate outcome and toxicity after Vero stereotactic body radiotherapy (SBRT) in early stage lung cancer, and feasibility of dynamic tumor tracking (DTT) with a single fiducial marker in this population. Material and Methods A prospective trial (NCT 02224547) was started to evaluate SBRT on a gimbaled linac (Vero) for early stage non-small cell lung cancer (T1-3N0M0). Patients were eligible for DTT if tumor motion on pretreatment 4DCT exceeded 8 mm. A single fiducial marker (Visicoil, IBA) was implanted percutaneously in or near the tumor. Otherwise an internal target volume (ITV) approach was applied, combining GTV’s of all 10 respiratory phases on 4DCT. For both approaches, an PTV- margin of 5mm was used from GTV (DTT) or ITV. Results