The dark side of the moon: risk of cancer induced by external beam radiotherapy of tumours
Warsaw Medical Physics Meeting 2015
Andrzej Wojcik1, Iuliana Toma-Dasu2 and Alexandru Dasu3
1: Centre for Radiation Protection Research, MBW Department, Stockholm University; 2: Medical Radiation Physics, Department of Physics, Stockholm University; 3: Department of Radiation Physics and Department of Medical and Health Sciences, Linköping University and Skandionkliniken, Uppsala, Sweden.
Nearly two-thirds of all cancer patients will receive radiation therapy during their illness. But ionising radiation is a two-edged sword: although it is effectively used to treat tumours, it can also induce cancer. For a long time the carcinogenic effects of radiotherapy were of minor importance, because increasing patient cure was the primary goal. Recently, in light of the large number of cancer patients undergoing high-dose (65–80 Gy) radiotherapy at younger ages due to early diagnosis, and with lengthy expected survival times, there is increasing concern regarding the risk of radiotherapy-induced second cancers. The concern is augmented by the growing use of new radiotherapy modalities, especially volumetric modulated arc therapy and protons.
There is considerable uncertainty about the carcinogenic effects of higher doses delivered locally to tissues surrounding a tumour due to difficulty of finding appropriate control groups that would permit a sound relative risk estimation in an epidemiological approach. Modelling is a way forward, but it suffers from the lack of reliable data on the long-term response of normal tissue cells to fractionated, high dose radiation, especially regarding the competitive relationship between cell killing and the induction of carcinogenic mutations.
The aim of the lecture is to give an overview of the state-of-the-art regarding the risk of radiotherapy-induced cancers.
40 minutes 12 seconds