Molecular RBE for thyroid cancer

Introduction Cancer risk following exposure to energetic heavy ions is a major issue for space exploration and cancer ion beam therapy (1). However, no epidemiological data for exposure to heavy ions are available. Papillary thyroid carcinoma (PTC) is a known radiation-induced tumour. Several molecular studies have been performed to investigate genes involved in PTC occurrence. Rearrangements in human chromosome 10 and in particular intrachromosomal exchanges are recognized anomalies associated with PTC formation (2). Assuming that this type of aberrations is a biomarker of PTC risk, we aimed to estimate the relative biological effectiveness (RBE) of heavy ions using a molecular marker in vitro. We measured intrachanges in human thyroid follicular cells exposed to sparselyor densely-ionizing radiation. The analysis of chromosomal aberrations was performed with the mBAND technique, which allows detection of both interand intra-chromosomal exchanges.