ESTRO 2020 Abstract book

S272 ESTRO 2020

reported. If stereotactic (body) RT was applied, the prescribed dose (range 16.0-37.5Gy) and fractionation schemes (range 1-7fx) varied considerable between centers. At least 60% of the centers use daily online position verification with correction of rotation and translation independent of the fractionation regimen, metastatic site or tumor type. Nearly all responders agreed that for metastatic disease, consensus on tumor dose prescription per tumor type and site, and protocol adaptations are much needed. Conclusion This international survey on the use of RT to metastatic sites from pediatric solid tumors demonstrates a wide range of practice. Participants agree that, given the lack of high quality evidence of the role of RT for metastatic disease in children with solid tumors, cooperative research groups are needed to conduct randomized trials of metastatic site irradiation to allow a meaningful consensus to be achieved. OC-0455 Palliative head and neck radiotherapy with the 'Hypo Trial' regimen for incurable cancers. M.J. Garcia Anaya 1 , R. Ordoñez Marmolejo 1 , M.D. Toledo Serrano 1 , J.A. Medina Carmona 1 , J. Gómez-Millán Barrachina 1 1 Hospital Universitario Virgen de la Victoria, Radiation Oncology, Malaga, Spain Purpose or Objective Patients with incurable H&N cancer have a generally poor prognosis. Although these patients are not candidates for curative treatment, they often require palliative cancer- directed therapy to relieve symptoms secondary to disease. The RT may be an option to mitigate disease- related symptoms. The treatment with palliative RT has been studied in retrospective studies and small phases 2 trials. However, there is no consensus on the optimal palliative radiation regimen. The aim of this study is to identify predictors of palliation in the hypofractionated treatment for incurable H&N cancer patients. Material and Methods We assessed retrospectively 106 consecutive patients with incurable (primary or nodal metastatic) H&N cancer, treated between January 2008 and December 2018. Treatment schedule of 30Gy or 36Gy in 5 sessions of 6Gy twice a week was used, as published in phase II trial ‘Hypo Trial’. Prognostic factors were analysed by Cox proportional hazards modeling. Multiple stepwise logistic regression was used to examine correlation between palliative response and clinical factors. Prognostic and clinical factors examined include age, sex, ECOG, stage, M1 at diagnosis, palliative chemotherapy, RT dose, pretreatment malnutrition, prior treatment, tumor volume and palliative response. Results Patient characteristics are shown in figure 1. ECOG was ≥2 in 61.9% patients. The histology was squamous cell carcinoma in all cases and the predominant primary site was larynx (32.1%). Local pain was the most common presenting symptom in 50.9% cases and odynophagia/dysphagia in 20.8% cases. Prescription dose was 30Gy in 58 patients (54.7%) and 36Gy in 48 patients (45.3%). With a median follow up of 6.92 months, 79.2% of the patients experienced any (partial or complete) palliation of the presenting symptom. 95 patients (89.6%) received the full dose initially prescribed, of them, only 14 (13.2%) did not achieve any palliation. On the contrary, 8 (7.5%) of 11 patients (10.4%) of those who did not complete the treatment presented no palliation. By

logistic regression, achieving a palliative response was significantly correlated with the radiation therapy dose received (p=0.01), ECOG (p=0.01) and no or mild malnutrition (p=0.01), but not with the rest of the clinical factors examinated. Overall the treatment was well tolerated. The most frequent grade 3 acute toxicity was mucositis (17%), while only few cases developed severe odynophagia (3.8%). Median OS and PFS was 7.4 months and 4.63 months, respectively. It should be noted that achieving palliation was statistically associated to OS (figure 2).

Conclusion This short palliative scheme resulted in excellent compliance and effective palliation with acceptable toxicity. Radiation therapy dose seems to be a predictive factor for palliation. As a result, an adequate selection of patients and an early referral treatment is a key factor. The challenge is to identify this subgroup of patients who will benefit from a high final equivalent biological dose of RT.