Abstract Book

S892

ESTRO 37

independent risk factors of metachronous bone metastasis of colorectal cancer within 5 years. Scoring was conducted by adding zero or one point from each variable and resulted in four groups of 0, 1, 2 or 3 points. Three groups were formed, with 0-1 points vs. 2 points vs. 3 points (1.5% vs. 6.6% and 10.5%, p<0.001). Conclusion This new score can help physicians to identify patients at risk for continuous monitoring and optimize surveillance management for patients to detect and treat bone metastasis very early in order to avoid the occurrence of skeletal complications. EP-1659 Superficial Hyperthermia+Radiotherapy: toxicity and outcome of 65 metastatic lesions G. Cattari 1 , A. Di Dia 2 , M. Gatti 1 , E. Delmastro 1 , G. Belli 1 , A. Salatino 1 , P. Gabriele 1 1 FPO-IRCCS Candiolo, Radiotherapy, Candiolo, Italy 2 FPO-IRCCS Candiolo, Medical Physics, Candiolo, Italy Purpose or Objective The association of superficial hyperthermia and radiotherapy (RT-HT) improves the clinical outcome and quality of life in patients with symptomatic lesions. In our Institute we perform superficial HT to offer an other treatment choice to advanced oncological diseases previously or not irradiated. We need to evaluate the safety, feasibility and toxicity of RT-HT association in superficial recurrent and metastatic tumors in this cohort of patients Material and Methods 42 patients (pts) (mean age 69 years; range: 47-95) with superficial recurrent/metastatic tumors were treated: 19 breast carcinoma, 11 head&neck cancer, 3 malignant melanoma, 4 sarcomas, 1 uterine adenocarcinoma, 1 hepatocarcinoma, 2 pancreatic carcinoma and 1 small cell cancer of thigh. The total number of treated lesions was 65. The mean Karnofsky Index value is 80. Pretreated pts (73%) received a mean radiotherapy dose of 50 Gy. Pts underwent radiotherapy treatment using 3D- conformal radiotherapy (17/42), Arc-Therapy (2/42) or Helical Tomotherapy (23/42). External beam radiotherapy was delivered in 5-30 fractions of 1.7-5 Gy to a total dose of 20-63 Gy (mean external dose: 40.3 Gy). HT is performed with a double electromagnetic superficial applicators operating at the frequency of 434 MHz. HT session was delivered once/twice weekly during the time of external radiotherapy, 1-2 hours after radiotherapy. Average, maximum and minimum temperature parameters were recorded during hyperthermia treatment. The treatment goal was to reach 40- 42°C in > 90% (T90) of measured points for a duration of 60 minutes. Acute and late toxicity was evaluated according to the CTCAE criteria. Local control was assessed after the end of the treatment on the basis of the RECIST Criteria Results During hyperthermia treatment the median temperature [range] reached was 40.5 °C [39 – 42.9°C]. 5 pts interrupted the treatment: 2 pts (5%) for G3 toxicity, 2 (5%) for poor compliance and 1 (2,4%) for clinical progression disease. 2 pts (5%) had acute cutaneous toxicity ≥ G3 at 1 month. 4 pt had toxicity > G2 at 3 months, three had > G2 at 6 months and only one patients at 12 months. No pts showed toxicity ≥ G2 thereafter. The mean follow-up was 13 months (range 1- 50 months). The Local control rate was: 88%, 78%, 68% ,61%, 71% and 75% at 1 , 3 , 6 , 12, 24, 36 months respectively. The time to local progression was ranged

between 1 and 36 months (mean:8 months). The detailed results are reported in Table 1. 10 pts are dead (9 for disease and one for vascular accident. Univariate analysis showed that Tmean, Tmax, Tmin, T90 parameters were not associated with local control rate Conclusion RT-HT is useful combined treatment with a good local control rate and patient compliance. The clinical outcome and the time duration of the follow-up is affected by the advanced stage of diseases. A larger pool and a more detailed patient stratification are needed to evaluate the outcome data in the time EP-1660 Clinical outcome after robotic radiosurgery for the management of intraorbital lesions I. Desideri 1 , G. Francolini 2 , V. Di Cataldo 2 , L. Masi 2 , G.A. Carta 3 , I. Meattini 3 , P. Bonomo 3 , M. Loi 3 , D. Greto 3 , L. Livi 3 1 Radiotherapy Unit- University of Florence, Department of Experimental and Clinical Biomedical Sciences-, Firenze, Italy 2 CyberKnife Center- I.F.C.A Istituto Fiorentino di Cura ed Assistenza- University of Florence, Robotic Radiosurgery, Firenze, Italy 3 University of Florence, Radiotherapy, Firenze, Italy Purpose or Objective Orbital lesions are are an uncommon eventuality, but are likely to become become symptomatic and impact on patients quality of life. Local control is often difficult to obtain, because of the proximity to critical structures. Cyberknife R robotic radiotherapy could constitute a viable treatment option in this kind of lesions . Here a retrospective experience about patients consecutively treated with stereotactic robotic radiotherapy in our Data from clinical records of patients consecutively treated for intraorbital lesions from solid malignancies were retrospectively collected, All patients undergone treatment with Cyberknife R system (Accuracy Inc., USA), with dose ranging from 10 to 35 Gy in 1-5 fractions. Simple descriptive statistic were used to analyze local control (LC), response rate, symptoms control, progression free and overall survival (PFS and OS), acute and late adverse events. Dosimetric data about Target coverage and dose to organs at risk are reported as well. institution is presented. Material and Methods

Results From January 2012 to May 2017, 20 treatments on 19 patients were performed in our institute, baseline characteristics are highlighted in table 1 . Patients were treated with dose ranging from 10 to 35 Gy in 1-5 fractions, prescribed at an average isodose line of 79,5% (range 78-81). After a mean follow up of 14,26 months (range 0-58) overall response rate was 75%, with 2 and 4