ESTRO 38 Abstract book

S735 ESTRO 38

patients, although with progression with additional pulmonary oligometastases, would still have a potentially curable oligometastatic disease and repeated ablative therapies could delay systemic treatment. Material and Methods From October 2011 to November 2016, a retrospective analysis was performed at 2 academic centre including patients treated with SBRT and TA for pulmonary oligometastases. Results Patient characteristics : A total of 198 lesions were treated for 102 patients; 45 patients (44.1%) underwent repeated focal treatment at the pulmonary site for an oligorecurrent disease. The median follow-up of the cohort was 22.5 months. Respectively, 29 patients, 12 patients and 4 patients had 2, 3 and 4 treatment sequences. The median interval between the first and the 2 nd , the 2 nd and the 3 rd , and the 3 rd and the 4 th sequence was respectively 13 months, 12.5 months and 10.5 months. A colorectal or renal primary cancer was found significantly more often in multi-treated oligorecurrent patients in contrast to a bronchopulmonary primary cancer. Treatment characteristics : The number of lesions treated by TA, SBRT and surgery are respectively 95, 103 and 14 lesions. 31 patients had a treatment combining several types of ablative techniques either to treat several pulmonary lesions during the same sequence, or during different treatment sequences. Patients treated with SBRT had more significantly central topography lesions compared to those treated with TA (p <0.005). Lesions treated with SBRT were significantly larger in diameter than those treated with TA (p = 0.003). Patient outcome: The 3-year overall survival rates of patients who had a single treatment sequence versus those with repeated treatments were respectively 73.9% and 78.8%, not significantly different (p = 0.86). The 3-year systemic therapy free survival of multi-treated oligorecurrent patients was 51.2%. In univariate analysis, only WHO status is significantly associated with OS (p=0.04). Tolerance of repeated treatments was excellent, one grade 4 toxicity was observed. Conclusion We established the first series of repeated multimodal local treatment for oligometastatic or oligorecurrent disease. These repeated treatments are effective with acceptable pulmonary toxicity. OS of patients treated with curative intent on several oligometastatic events is similar of those treated for a single oligometastatic event. Ablative treatments of their oligometastases may delay the use of systemic treatments, with the clinician's main concern being the maintenance of quality of life. EP-1344 Helical Tomotherapy based SBRT in early stage lung cancer: a mono-institutional study (2014- 2018) F. Pastore 1 , A. Rese 1 , F. Francomacaro 1 , F. Cammarota 1 , G. Ametrano 1 , D. Toledo 1 , V. Iorio 1 1 Emicenter, Radiation Oncology, Mondragone, Italy Purpose or Objective To evaluate the use of Helical Tomotherapy (HT) based SBRT in the treatment of early stage lung cancer patients. The HT system employs a compact 6 MV Linac-based on CT ring gantry to rotationally deliver intensity modulated fan beams. Patients are translated through-out the gantry on a treatment couch, resulting in helical irradiation geometry. The HT unit also contains a mega-voltage CT detector array located opposite the radiation source for pre-treatment verification, allowing accurate re- positioning. This technique permits to precisely target tumors while minimizing impact on surrounding healthy tissue.

EP-1342 SBRT for central lung malignancies using a Simultaneous Integrated Protection (SIP) approach R. Mazzola 1 , R. Ruggieri 1 , F. Vanessa 1 , R. Michele 1 , G.L. Niccolò 1 , R. Francesco 1 , N. Luca 1 , C. Stefanie 2 , A. Filippo 1 1 Sacro Cuore Don Calabria Cancer Care Center, Radiation Oncology, Negrar, Italy ; 2 University Hospital- LMU, Radiation Oncology, Munich, Germany Purpose or Objective It is recognized that Stereotactic Body Radiotherapy (SBRT) for centrally located lung malignancies is affected by high rates of severe toxicity. In the present study, we report the clinical outcomes following a novel intensity- modulated radiotherapy prescription dose, termed simultaneous integrated protection (SIP) for nearby organs at risk (OARs). Material and Methods The present study is a mono-institutional prospective observational study. The inclusion criteria were: single central lung lesion receiving SBRT; absence of extra- thoracic disease; Karnofsky performance status > 70; maximum tumor diameter < 5 centimeters (cm); at least 6 months of follow up after SBRT. Lung malignancies were defined as central according to the International Association for the Study of Lung Cancer (IASLC) recommendations (i.e., tumor within 2 cm to any mediastinal critical structure). The prescribed total doses of SBRT were: 70 Gy in 10 fractions and 60 Gy in 8 fractions. For ultra-central located lesions, a dose of 60 Gy in 10 fractions was delivered. The main planning instructions were: (1) to remain within the limits of the given dose constraints for an OAR; (2) to make use of the maximum possible dose to the OARs to minimize dose inhomogeneity for PTV. SBRT-related toxicity was prospectively assessed according to Common Terminology Criteria for Adverse Events (CTCAE) v4.0. The primary clinical end-point was the toxicity SBRT-related. Secondary endpoint was local According to the inclusion criteria of the present analysis, 40 patients affected by a single central malignancy were selected. The median follow up was 20 months (range 6- 58 months). The median age was 72 years (range 30-81 years). The median distance between tumor and mediastinal healthy structures was 0.6 cm (range 0- 1.8 cm). The one- year local control rate was 91%. The median time to local progression was 13 months (range 6-46 months). One-year distant progression free survival rate was 71.7%. At the time of the analysis, the 1- and 2- years overall survival rates were 86.9% and 72.6%, respectively. Acute and late clinical pulmonary toxicity ≥ grade 2 were recorded in 2 out of 40 patients (5%) and 3 out of 40 patients (7%). No patient experienced cardiac toxicity. No narrowing or stenosis of any airway or vessel was control. Results SBRT using a PTV-SIP approach for single central lung malignancies allowed to achieve low toxicity SBRT-related with acceptable local control. EP-1343 Multimodality Repeated-Ablative Therapies In Oligorecurrent Pulmonary Metastatic Disease A. Macagno 1 1 Paoli-Calmettes Institute, Radiotherapy, Marseille, France Purpose or Objective Stereotactic radiotherapy (SBRT) and percutaneous thermal-ablation (TA) are surgery alternatives for the management of pulmonary oligometastases. In this collaborative work we analysed patients who undergone iterative focal ablative treatments on pulmonary oligometastases. We hypothesized that some of these registered. Conclusion