Abstract Book

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ESTRO 37

Results Between 2003 and 2013, 35 patients with resectable localized RPS were treated. Median age was 59.2 years. About half of the patients were male (53.3%). Main histological subtypes were dedifferentiated liposarcoma (34.7%) and well differentiated liposarcoma (22.7%). Median tumor size was 16.4 cm and most of the patients had grade II and III tumors (45.3% and 28%, respectively). Eighteen patients (51%) developed local (33%) or distant (12%) or both local and distant (6%) relapse. Five-year disease free survival (DFS) was 46.6% and overall survival (OS) was 63.2%. Histology and FNCLLC grading were statistically significantly associated with OS (p= 0.024 and p= 0.005, respectively). Thirteen patients developed LR, of whom 5 patients developed concurrent distant metastases (DM). Seven patients developed metastases (DM), of whom the majority to lung. Histological subtypes resulted statistically significantly associated with DM (p: 0.036). All patients completed RT while 4 patients did not completed CT due to hematological toxicity. More than 60% of patients presented grade I-II gastrointestinal toxicity (nausea, vomiting) (N=22). Fatigue was presented by 68% of patients, in 5 patients of grade III. In 3 cases severe perioperative morbidity occurred; in particular 2 patients presented anastomotic leakage, in the other case a retroperitoneal abscess was present. Conclusion Neoadjuvant RT with concomitant CT followed by surgery seems to be an effective approach in the management of RPS. Prospective trials are needed to better understand who are the patients who will benefit the most from this kind of treatment. EP-1637 Early results of spot-scanning proton therapy with hyperthermia in large inoperable sacral chordomas M. Walser 1 , N. Datta 2 , E. Puric 2 , B. Bachtiary 1 , U. Kliebsch 1 , R. Schneider 3 , S. Bodis 2 , D. Weber 1 1 Paul Scherrer Institute PSI, CPT, Villigen PSI, Switzerland 2 Cantonal Hospital Aarau, Radiation Oncology, Aarau, Switzerland 3 Helios Medical Center Schwerin, Radiation Oncology, Schwerin, Germany Purpose or Objective Large inoperable sacral chordomas show unsatisfactory local tumor control rates even when treated with high dose proton therapy (PT). The addition of hyperthermia to radiation therapy leads to improved results in the treatment of sarcomas. The aim of this investigation is to analyze the feasibility and early results of a novel treatment in large inoperable sacral chordomas with high dose PT and local hyperthermia (HT). Material and Methods Eligible patients had histologically proven sacral chordomas. Pencil beam spot scanning proton therapy was delivered with a 250 MeV Cyclotron. Prescribed tumor dose was 70 Gy (RBE) in 28 fractions over 5½ weeks. In 4 (80%) patients, the 70 Gy (RBE) was prescribed to the GTV within a simultaneous integrated boost concept. The PTV, containing the area of possible microscopic disease plus a 7 mm security margin received 56 Gy (RBE). In one patient, the 70 Gy (RBE) was prescribed to the PTV which was the GTV plus 5 mm for CTV and additional 7 mm security margin. Hyperthermia was delivered once a week immediately after proton therapy using the Sigma 60 or Sigma-Eye applicator with

the BSD 2000 deep hyperthermia unit. All patients received up to 6 hyperthermia sessions during the proton therapy. Temperature was monitored on the skin, in the rectum, gluteal fold and the urinary bladder. Acute and late toxicity was assessed according to CTCAE v4. Results From June 2016 to October 2017, 5 male patients were treated with PT and HT. Median patient age was 67 years (range, 57-71) and they had a median tumor size of 791 cc (range, 457-1361). Median follow-up (FU) was 6 months (range, 0-9). Median HT session number was 5 (range, 2-6). FU imaging showed slight tumor decrease in 3 patients at 6, 8 and 9 months following treatment. Last MRI showed stable disease in one patient and one patient had no FU imaging yet. Three patients presented initially with pain while two in addition had numbness. Three patients had initial dysuria. All 5 patients developed increased pain during the therapy and needed analgesics. None had ≥ 3 acute or late toxicities. Pain and numbness recovered in all during follow-up. Conclusion Early results in patients with large inoperable sacral chordomas undergoing combined treatment of PT and HT are encouraging with no grade ≥ 3 acute and late toxicities. All patients showed a significant reduction in their initial pretreatment symptoms. Early follow-up imaging showed either slight regression or stable tumor size. Initial clinical pretreatment symptoms decreased during FU in all patients. Therapy showed no grade ≥ 3 acute or late toxicities. These results are promising and warrant further confirmation in a prospective trial with a larger number of patients and a longer FU period. EP-1638 Trento Proton Therapy Centre Experience For Spine Chordoma, Chondrosarcomas And Other Sarcomas I. Giacomelli 1 , M. Cianchetti 1 , F. Dionisi 1 , D. Amelio 1 , D. Scartoni 1 , S. Vennarini 1 , M. Amichetti 1 1 Centro di Protonterapia, Protontherapy, Trento, Italy Purpose or Objective To report the initial clinical experience of Trento Proton Therapy Centre in treating chordomas (C), chondrosarcomas (CS) and other sarcomas (S) with protontherapy (PT) in terms of safety and feasibility. Material and Methods From December 2014 to September 2017 44 patients (pts) and 45 lesions were irradiated with protontherapy (PT). Mean age was 62.6 years (range: 17,8 – 84,1); mean KPS was 90 (range 50-100). There were 32 C, 5 CS, 1 Osteoblastoma and 1 Giant Cell Tumor, 1 Dedifferentiated Liposarcoma, 1 Malignant Peripheral Nerve Sheath Tumor, 1 Hemangioendothelioma, 2 Solitary Fibrous Tumor, 1 Leiomiosarcoma. Tumors were located in sacrococcyx n= 18, lumbar spine n= 13, cervical spine n= 8 and dorsal spine n= 6. Median diameter at the time of treatment was 60 mm (range 24-128). Ten lesions were only biopsied and treated with exclusive PT. Thirty five lesions had been treated with ≥ 1 surgery, of them 23 cases had gross residual disease at the beginning of PT in those cases PT was performed with radical intent, 12 cases were treated with adjuvant intent. Five macroscopical diseases had already previously been irradiated, 4 of them with photons at a total dose of 36 to 54 Gy and one, with protons at a total dose of 66 GyRBE. Toxicity was scored according to the CTCAE 4.0, pain was scored according to the Numerical Rate Scale (NRS).