ESTRO 2020 Abstract book

S466 ESTRO 2020

not been reported yet. Unfortunately, no randomized studies are published on the effect of radiotherapy on both LD and DD. Therefore, in some countries radiotherapy is not covered by the insurance companies. Currently, some randomized studies are running to find more evidence on the effect of radiotherapy. Also new therapies, like hormonal treatment, collagenase injections and ultrasonic treatment are under investigation for both LD and DD. SP-0765 Brachytherapy in management of (recurrent) keloid L. Tagliaferri 1 1 fondazione Policlinico Universitario Agostino Gemelli Irccs, Gemelli Art Advanced Radiation Therapy - Interventional Oncology Center Ioc, Rome, Italy Abstract text Keloids are in the group of irregular fibrous tissues, which develop at the site of a scar or injury of the skin. If keloids are treated with surgery alone, there is a recurrence probability up to 50%. Although, the scientific basis and experimental proof in this field remains still inadequate, numerous treatment methods have been proposed for keloids. The efficacy of adjuvant radiation therapy in the management of keloids has been demonstrated if the radiation starts within 48 hours postoperatively. Indeed, postoperative radiotherapy is a useful treatment option that has shown to be more effective compared to surgery or radiation therapy alone. The adjuvant irradiation can be delivered using X-ray, electron beam or brachytherapy (BT, interventional radiotherapy, IRT). Because of the low alpha/beta ratio of keloids, hypofractionation is an advantage. IRT is safe and effective and offers several advantages compared with external beam radiotherapy (EBRT). The main advantages are the possibility to deliver higher doses in the area of the surgical bed reducing the dose to the adjacent organs at risk and a short treatment time. In this scenario, HDR seems to be one of the best radiation modalities available with post-irradiation recurrence rates of 3% to 44%. Indeed, comparing recurrence rates between different radiation modalities, IRT seems to have a lower recurrence rate when compared to electron beam and X- ray therapy and less toxicity to adjacent organ at risk. The choice of the radiation technique should be based on its availability, patient comfort, local experience and hospital budget size. However, one of the most important considerations is to select the most appropriate patient population for this treatment strategy and this should be performed in experienced and trained hands. Despite this evidence, IRT is not defined as a gold standard and seems to be underused. Due to the lack of strong recommendations in the treatment of keloids, clinical decision-making may be influenced by the hospital of diagnosis. In conclusion, adjuvant radiotherapy for the treatment of keloids seems to be superior to radiation or surgery as monotherapy. IRT resulted to be safe and feasible. The precise lesion-targeted irradiation with the most normal tissue sparing, which results in improved esthetic appearance, will ensure better patient satisfaction and clinical outcome.

Joint Symposium: ESTRO-ESR: Online MR-guided radiotherapy - Where are we right now?

SP-0766 The radiologist prospective N. Lev-Cohain 1 1 Hadassah Medical Center, Radiology, Jerusalem, Israel Abstract text The increased use of magnetic resonance imaging (MRI) in radiation therapy (RT) caused the use and development of MRI-guided treatment systems. MRI provides better anatomical detail for RT treatment planning as well as for post treatment response assessment. This session will discuss the MRI advantages with emphasis on increased resolution of the targeted lesion, as well as the challenges- such as motion, and its adaptive capabilities. The capacity of the MRI to evaluate post-treatment tissue viability with increased accuracy, will also be reviewed. SP-0767 Clinical indications - Rationale and strategies M. Intven 1 1 UMC Utrecht, Radiation Oncology Department, Utrecht, The Netherlands Abstract text The clinical benefits of online MR-guided radiotherapy are twofold: imaging with better soft tissue contrast than with cone-beam CT and the possibility of daily online treatment plan adaptation. Clinical indications for MR-guided radiotherapy are indications which benefit from one or both of these opportunities. In this lecture typical clinical examples of such treatment sites are shown, like rectal cancer, pancreatic cancer and oligometastases. Besides, also the workflow on a 1.5T MR-linac is discussed. SP-0768 Motion-based treatment delivery L. Boldrini 1 1 Fondazione Policlinico Universitario "A. Gemelli" IRCCS, Radiation Oncology, Rome, Italy Abstract text The talk will focus on motion management solutions offered in clinical Magnetic Resonance guided Radiotherapy. Target motion will be described in the different anatomical sites highlighting site specific mitigation strategies and the available clinical evidence. More specifically, patients selection and positioning, breathing control solutions and visual feedback approaches will be presented in the different clinical scenarios. SP-0769 Online MR-guided radiotherapy - Adaptation by size or function S. Bhide 1 1 the Institute Of Cancer Research And The Royal Marsden Nhs Foundation Trust, Head And Neck And Gi Oncology, Sutton, United Kingdom Abstract text HPV+ve oropharyngeal Cancer (OPC) is associated with markedly improved prognosis compared to non-HPV- associated OPC. The favorable prognosis, along with the long-term survival is the basis for treatment dose- escalation. While tumor responsiveness to radiotherapy in OPC has been shown to be associated with permanent tumor control outcomes, intra-treatment tumor shrinkage