ESTRO 2021 Abstract Book

S1215

ESTRO 2021

increasingly referred. No international guidelines or consensus exist on whether or how to combine these drugs with radiotherapy. Therefore, the purpose of this study was to investigate the current clinical practice in the Netherlands regarding hypofractionated radiotherapy in patients using targeted drugs and immunotherapy. Materials and Methods A survey was sent to all 21 Dutch radiotherapy institutions via the Dutch Society for Radiotherapy and Oncology (NVRO). Dedicated radiation oncologists (ROs), medical oncologists (MOs) and pulmonologists (Ps) were asked to fill out the survey. The questions explored their familiarity with the combination of targeted drugs and immunotherapy with radiotherapy, encountered clinical difficulties and (factors influencing) treatment decisions. Results The survey was filled out by 54 respondents from 19 different institutes (27 ROs, 10 MOs and 17 Ps). The median annual number of patients per RO referred for radiotherapy when using targeted drugs or immunotherapy was 10 and 15, respectively. Despite this high number, only 11% of ROs state that they have sufficient information (resources) for adequate treatment decision making. Just 31% of all respondents (strongly) agree that there is sufficient knowledge within their institute regarding this topic. A multidisciplinary protocol is rarely available (17%) and the application of radiotherapy treatment adaptations (technique, dose, fractionation, field size) varies widely. ROs, MOs and Ps have different opinions about the toxicity of drug-radiotherapy combinations and the risk of tumor flare upon temporary drug discontinuation (Fig. 1).

Conclusion Radiotherapy referral during targeted drugs or immunotherapy occurs regularly in clinical practice. There is no consensus amongst involved medical specialties on toxicity and whether to combine or discontinue systemic treatment. An urgent need for multidisciplinary, evidence-based guidelines for the optimal management of these patients exists. It is necessary to perform clinical studies examining the safety of these combined treatments and to incorporate radiotherapy into phase I-III clinical trials for new targeted drugs and immunotherapy. PO-1484 Impact of COVID-19 pandemic on Radiation Oncology practice. An overview of recent higher quality reports R. Carbonara 1 , M.P. Ciliberti 1 , F. Gregucci 1 , A. Surgo 1 , M. Caliandro 1 , R. Tucciariello 1 , G. Masiello 1 , I. Bonaparte 1 , A. Fiorentino 1 1 General Regional Hospital F.Miulli, Radiation Oncology Department, Acquaviva delle Fonti (Bari), Italy Purpose or Objective Worldwide, the COVID-19 pandemic seems to significantly impact on cancer care due to emergency-related conditions. To synthetize the emerging changes in multiple fields of Radiation Oncology (RO), we report an overview of clinical experiences and practical proposals published since the beginning of the emergency period of COVID-19 pandemic