ESTRO 2021 Abstract Book

S726

ESTRO 2021

1 Gemelli Molise Hospital – Università Cattolica del Sacro Cuore, Radiation Oncology Unit, Campobasso, Italy; 2 Gemelli Molise Hospital – Università Cattolica del Sacro Cuore, Medial Physics Unit, Cmapobasso, Italy; 3 Gemelli Molise Hospital – Università Cattolica del Sacro Cuore, Medical Physics Unit, Campobasso, Italy; 4 Alma Mater Studiorum Bologna University, Department of Experimental, Diagnostic, and Specialty Medicine - DIMES, Bologna, Italy; 5 IRCCS Azienda Ospedaliero-Universitaria di Bologna, Radiation Oncology, Bologna, Italy; 6 Fondazione Policlinico Universitario A. Gemelli, IRCCS, UOC di Radioterapia, Dipartimento di Scienze Radiologiche, Radioterapiche ed Ematologiche, Roma, Italy; 7 Università Cattolica del Sacro Cuore, Istituto di Radiologia, Roma, Italy Purpose or Objective To report the final results of a dose escalation study of volumetric intensity modulated arc radiosurgery (VMAT-SRS) boost after 3D-conformal radiotherapy (3D-CRT) in patients with isolated spinal metastases (iSM). Materials and Methods Patients with iSM and less than 5 visceral metastases were included in this study. 25 Gy 3D-CRT radiotherapy was delivered in 10 daily fractions (2 weeks) to metastatic lesion, affected vertebrae and adjacent ones (one cranial and one caudal vertebrae). Sequentially, the dose to spinal metastasis (plus a personalized margin) was progressively increased (8 Gy, 10 Gy, 12 Gy) in the patient cohorts. Dose-limiting toxicities (DLTs) were defined as any treatment-related non-hematological acute adverse effects rated as G ≥ 3 or any acute hematological toxicity rated as ≥ 4 by RTOG scale. Results Forty seven lesions accounting for 41 consecutive patients (M/F: 30/11; median age: 69 years; range 38-85) were treated from November 2010 to June 2020. Most patients had a primary prostate (63.4%) or breast cancer (24.4%). Twenty-seven patients received 8 Gy VMAT-SRS boost (total BED 10 : 45.7 Gy), 13 patients received 10 Gy (total BED 10 : 51.3 Gy), and 7 patients received 12 Gy (total BED 10 : 57.6 Gy). With a median follow-up of 15.2 months (range 1-91), no acute toxicities > grade 2 (Table 1) and no late toxicities > grade 1 were recorded. Overall response rate based on CT/PET-CT/MR was 61.7% with a complete response rate of 55.3%. Two year-actuarial local control (defined as irradiated site progression-free) was 89.4%, while the 2 year-actuarial overall survival was 90.1% .

Conclusion A VMAT-SRS boost on iSM delivered after a 25 Gy 3D-CRT to adjacent vertebrae resulted to be feasible with encouraging tumor response, local control rate and toxicity profile.

PD-0888 How timely is timely when it comes to palliative radiotherapy? 14 days or is it Urgent Plus? L. Bedford 1 , J. Walther 1 , U. Barthakur 1 , A. Davis 1 , S. Donickey 1 1 Musgrove Park Hospital, Radiotherapy, Taunton, United Kingdom Purpose or Objective Objective: To develop and implement a rapid pathway for patients who require palliative radiotherapy in a shorter timeframe than 14 days 1 . Palliative radiotherapy is often used for patients with very advanced disease or a poor prognosis that requires speedy symptom management. There are also too often pleading discussions between the consultant and the scanning or treatment teams about “starting this patient as soon as possible” and whilst this is often achieved there is not always an audit trail or the justification criteria documented. Using and expanding on the role of the consultant radiographer (CR) led palliative service already in place an Urgent + pathway idea started. Materials and Methods Method: In consultation with all stakeholders an Urgent + (four working days) pathway has been developed, with defined eligibility criteria and pathway timelines. The eligibility criteria are for referral onto this urgent + pathway is: Impending cord compression; pain not responding to other forms of palliation; airway compromise, rapidly progressing disease, bleeding or other. Day zero is taken as being the day of referral and radiotherapy treatment is then delivered within four working days. All referrals and treatments for any palliative radiotherapy are already collected locally on a database and peer reviewed by a multi-disciplinary team, led by the CR. The database was expanded to include the Urgent + pathway for ease of audit and oversight. Results