ESTRO 2020 Abstract Book

S133 ESTRO 2020

Abstract text This presentation will review the rationale for SBRT in patients with low metastatic burden disease and the potential clinical settings in which SBRT can be applied. Data relating to oncological and toxicity endpoints will be presented and the current clinical and trial landscape reviewed.

SP-0259 ATR inhibitors can modulate the immune tumour microenvironment after radiation M. Dillon 1 1 Institute of Cancer Research, Chester Beatty Laboratories, London, United Kingdom Abstract text ATR inhibitors (ATRi) are effective radiosensitisers in vitro and in vivo [1]. Clinical trials are in progress to examine safety and efficacy of combined ATRi and radiation [2]. Emerging data show that ATRi may also cause significant modulation of the immune tumour microenvironment when combined with radiotherapy [3]. Data on micronucleation, changes in cellular infiltration from in vivo models and early clinical results will be presented. 1. Radiosensitization by the ATR Inhibitor AZD6738 through Generation of Acentric Micronuclei. Mol Cancer Ther, 2017. 16(1): p. 25-34. 2. PATRIOT: A phase I study to assess the tolerability, safety and biological effects of a specific ataxia telangiectasia and Rad3-related (ATR) inhibitor (AZD6738) as a single agent and in combination with palliative radiation therapy in patients with solid tumours. Clin Transl Radiat Oncol, 2018. 12: p. 16-20. 3. ATR Inhibition Potentiates the Radiation-induced Inflammatory Tumor Microenvironment. Clin Cancer Res, 2019. 25(11): p. 3392-3403. SP-0261 Unknown to the unknown: breast cancer brain metastases O. Kaidar-Person 1 1 Sheba Medical Center, Radiation Oncology, Ramat Gan, Israel Abstract text The management of breast cancer patients with brain metastases should be in correlation with the breast cancer molecular subtype, status of systemic disease, and other prognostic factors. Treatment is often challenging as there are different modalities available; different disease “behaviors” with some patients having indolent disease while others progress fast and advancement of systemic therapies may lead to control of systemic disease with devastating progressive intracranial disease. It is imperative that the treatment approach should be based on multidisciplinary discussion, taking into account survival benefit, patient’s wishes, quality of life and survival. SP-0262 Management of extracranial disease with stereotactic radiotherapy A. Kirby 1 1 Royal Marsden & Institute Cancer Research, Radiotherapy, London, United Kingdom Symposium: Multimodal approach to oligometastatic breast disease: current state-of-the-art SP-0260 Treatment of oligometastatic breast cancer based on biology S. Rivera Institut Gustave Roussy, Villejuif, France Abstract not received

Symposium: The role of radiotherapy in locally advanced pancreatic cancer

SP-0263 What is the optimal dose and fractionation? M. Hawkins 1 1 University College London, Dept. Of Medical Physics And Bioengineering, London, United Kingdom Abstract text The role and timing of radiotherapy in pancreatic cancer is subject to controversy and there is debate regarding the dose schedule. For patients with borderline resectable pancreatic cancers neoadjuvant therapy regimen of systemic chemotherapy followed by conventionally fractionated RT (25 fractions) with chemotherapy, moderately hypofractionated (15 fractions) of stereotactic ablative radiotherapy (SBRT) 5 fractions are accepted schemes. For patients with locally advanced pancreatic cancer, not suitable for surgery despite a definitive therapy regimen of systemic chemotherapy, there are three main approaches: conventionally fractionated radiotherapy with concurrent chemotherapy, dose- escalated fractionated chemoradiation, or multifraction SBRT without chemotherapy. Ongoing and published clinical trials are testing and supporting the various doses and fractionations. As systemic treatments are improving the outcomes in pancreatic cancer, radiotherapy continue to play a key role in controlling local disease, and multidisciplinary team discussion is necessary for selecting the best radiation dose and schedule combination in each setting. SP-0265 Is there a role for particle therapy in the treatment of locally advanced pancreas cancer ?" P. Fossati 1 , P. Georg 1 , E. Hug 1 1 EBG Medaustron Gmbh, Radiotherapy, Wiener Neustadt, Austria Abstract text Cancer of the exocrine pancreas can still be considered an unsolved clinical problem. An epidemiological analysis form 2012 has shown that in Europe incidence equals mortality. This dismal outcome is driven both by the high rate of patients that are already metastatic at diagnosis (or that develop metastases early in the course of their disease) and by the difficulties in achieving local control even in the non-metastatic patients. Aggressive chemotherapy can achieve a survival advantage both in metastatic and locally advanced cases. Radiotherapy has been used in the attempt to increase local control both preoperatively, and postoperatively but its role as exclusive local treatment is still questionable. Particle therapy with protons or carbon ions has several dosimetric advantages in comparison with standard radiotherapy with SP-0264 What is the target volume? F. Huguet Hôpital Tenon. Paris Cedex, France Abstract not received