Ionising radiation is a two-edged sword with respect to cancer. On the one hand it is successfully used for treating malignant tumours; on the other hand it is a well-known carcinogen. During the last decades the life expectancy for many cancer patients has increased due to improvements in both early detection and therapy methods and therefore late effects become a matter of concern for the long term survivors of cancer therapy. Radiation-induced cancers are increasingly mentioned among these concerns, albeit they are still regarded as the inevitable price for success of modern radiation treatment. However, a broad array of treatment techniques and equipment, including heavy ions and protons, are nowadays available which are capable of delivering variable, but therapeutically isoeffective dose distribution patterns to tumours and healthy tissues. Hence, including the aspect of cancer risk in the treatment optimisation process is possible and becomes increasingly important. Nevertheless, major concerns are uncertainties about the level of risk from modern techniques, the lack of appropriate control groups in epidemiological studies, insufficient knowledge about mechanisms of cancers induced by radiotherapy, including the influence of reverse causation, and the lack of data about the relationship between cancer-inducing genetic effects and cell killing in tissues receiving fractionated radiation doses and dosimetric uncertainties.

This workshop aims to revisit the Janus-faced nature of radiotherapy with respect to cancer from a multidisciplinary perspective. It will address the four pillars on which the study of the risk of secondary cancer stand: Epidemiology, Radiobiology, Dosimetry and Mathematical Modelling. Each of these will have a dedicated session complemented by discussion sessions merging the different perspectives. We hope that the workshop will generate new ideas and approaches to estimate the risk of secondary cancers leading to a safer use of radiotherapy.

A Focus Issue of Physica Medica: European Journal of Medical Physics (http://www.physicamedica.com), one of the most active European forums  on the applications of physics in biology and medicine, will be dedicated to the “Risk of secondary cancer following radiotherapy”.  

This comprehensive focus issue will present the outcome of the workshop organised in Stockholm, 8-9 September 2016. The Focus Issue will follow the same structure as the workshop and will include four sections on: Epidemiology, Radiobiology, Dosimetry and Mathematical Modelling.