ESTRO 2020 Abstract Book

S421 ESTRO 2020

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

the second analysis – the data collecting and analysis is ongoing. Treated group comprised 37 patients (median of symptoms duration 13 months) treated with 6 MV photons using the fraction dose of 1 Gy up to TD of 6 Gy. During the first control the complete pain relief reported 42% of patients, larger than 50% and smaller than 50%, 25% and 8% respectively. Conclusions: The obtained results permit us to form the conclusion that radiotherapy of painful inflammatory diseases is a very safe (no adverse effects observed) and very effective treatment modality, and considering its simplicity (simple technique) and low cost, should be more commonly taken into account. Comparing older and actual results, we do not see any positive impact of modern radiotherapy equipment on the treatment results; contrarily – the results seem to be worse. SP-0764 (Re-)Irradiation in Morbus Dupuytren and Ledderhose R. Steenbakkers 1 1 UMCG University Medical Center Groningen, Radiation Oncology, Groningen, The Netherlands Abstract text Dupuytren’s disease (DD) and Ledderhose disease (LD) are both a fibroproliferative condition of the hand and feet, respectively. DD or palmar fibromatosis is quite common disease and the prevalence is estimated to be 1-6%, especially at older age in northern Europe. Eventually, DD results into a progressive digital flexion contracture, mainly involving the little finger and ring finger, which hampers the function the hand. LD of plantar fibromatosis is a uncommon disease. The prevalence is not really known, but estimated to be less than 0.1 %. LD appears as one or more subcutaneous painless nodules which grow slowly and might become symptomatic (painful) during walking or in standing position and are sometimes very disabling when they increase in size. Treatment for DD, invasive strategies are injections of collagenase clostridium histolyticum, needle fasciotomy and extended surgical intervention. Most common non- invasive treatment is radiotherapy, which results into regression of symptoms or lack of progression. Invasive treatment for LD is not recommended. Currently, only radiotherapy seems to be beneficial for LD, resulting into regression of symptoms. Long-term side-effects using radiotherapy for DD and LD are uncommon. Skin dryness is observed in 25% of the treated patient. Radiotherapy induced malignancies have 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