Radiotherapy (RT) is one of the main approaches for cancer treatment used alone or in combination with chemotherapy. Different types of radiation beams are currently used, such as photons or charged particles such as protons and carbon ions (12C). Radiation enables to kill proliferating cancer cells, while limiting the effects on healthy tissues. The main cellular target of ionizing radiation is the DNA. In general, RT works by causing cellular genomic damages, either directly by interacting and injuring DNA, or indirectly ionizing water molecules. The later induces the formation of Reactive Oxygen Species (ROS), such as superoxide anion (•O−2), singlet oxygen (1O2), the hydrogen peroxide (H2O2) and the extremely reactive hydroxyl radical (•OH) that may alter the DNA and protein structures, as well as lead to lipid peroxidation.

Oxygen, thus, is one of the most effective dose-modifying agents, sensitizing cells to radiation. Oxygen causes an “amplification” of radiation-induced DNA damage, which is commonly described by the oxygen enhancement ratio (OER). The OER varies between 1 and approximately 3, respectively, when going from hypoxic (no oxygen) conditions to normoxic conditions of irradiation. As consequence, tumour oxygenation can decide the success of the radiotherapy treatment for patients, where oxygen has to be present at the time of the radiation delivery to allow for increased DNA damage. On the other hand, healthy organs are highly oxygenated and as consequence might be very sensitive to radiation.

The aim of this workshop is to summarize and review the current knowledge on the role of oxygen in radiation therapy and the ways of accounting for it in vivo. There are many factors that, to different degrees, influence the responses of both normal and cancer tissues to radiation in the presence of oxygen. What is the contribution of oxygen to radiation damage? How does oxygen impact radiation response of cancer and healthy tissue? Can oxygen damage be modulated to reduce radiation toxicity or to improve tumour control? Is it possible to predict individual response to radiation exposure in relation to the oxygenation of the tumour but also the healthy organs? The answer to these questions requires close collaboration between researchers in the fields of Radiobiology, Physics, Radiation Oncology and Biostatistics. Experts from each field will present their views in an attempt to integrate the different perspectives and come up with new approaches to answering the questions.

We hope that this workshop will continue in the spirit of our previous workshops (2014 - New school versus old school radiobiology, 2016 - The risk of second cancer from therapeutic irradiations, and 2018 - Current challenges of patient re-irradiation) and generate new ideas that will ultimately improve both radiological protection of healthy individuals and the safety and efficacy of treating cancer patients.

Organisers:

Iuliana Toma-Dasu - Medical Radiation Physics, Stockholm University and Karolinska Institutet

Joao Seco - German Cancer Research Center - DKFZ, Heidelberg, Germany

Emely Kjellsson Lindblom - Medical Radiation Physics, Stockholm University and Karolinska Institutet

Andrzej Wojcik - Centre for Radiation Protection Research, Stockholm University

Invited speakers:

Morten Busk – Aarhus University, Denmark

David J. Carlson – Yale University School of Medicine, Yale-New Haven Health, Department of Radiation Oncology, US

Joe Deasy – Memorial Sloan Kettering, New York USA

Bernard Gallez – Universite Catholique de Louvain, Belgium

Michael Horsman – Aarhus University, Denmark

Susanta Hui – Radiation Oncology, Beckman Research Center, City of Hope National Medical Center, Duarte, CA, US

Ron Leavitt – Centre hospitalier universitaire vaudois, Lausanne University Hospital, Lausanne Switzerland

Loredana Marcu – University of Oradea, Romania

Ejung Moon – University of Oxford, UK

Pierre Montay-Gruel – University of Antwerp, Belgium

Brian Pogue – University of Wisconsin, Madison USA

Emanuele Scifoni – Trento Institute for Fundamental Physics and Applications, Italy

Walter Tinganelli - GSI Helmholtzzentrum für Schwerionenforschung, Germany

About the workshop