Several sources of ionising radiation are classified by the International Agency for Research on Cancer (IARC) as causes of bone tumours, including plutonium, radium-224, -226 and -228, X-radiation and gamma-radiation.
Exposure to ionising radiation increases bone sarcoma risk, and risk appears to increase in line with exposure levels, though most evidence is on absorbed doses between 5 and 20 Gray (Gy), and many studies define bone sarcoma by anatomical site rather than morphology. Typical sources of exposure are radiotherapy medical diagnostics (e.g. X-rays), and natural background radiation (e.g. radon.)
Radiotherapy for cancer during childhood appears to have the greatest impact on bone sarcoma risk; however confounding is possible because much evidence includes populations with primary retinoblastoma, which in itself is associated with bone sarcoma risk.[2,4] Childhood cancer survivors who received around 20Gy from radiotherapy have around 6-38 times higher bone sarcoma risk compared with those who had no radiotherapy or very low doses; bone sarcoma risk increases with radiation doses received.[2,4] Abdominal/pelvic radiotherapy during childhood is associated with 3.1 times increased bone tumour risk, compared with no radiotherapy; radiotherapy to other body sites showed no significant effect in a British cohort study.
Radiotherapy for cancer (other than bone cancer) during adulthood is associated with 2.4 times increased risk of subsequent bone sarcoma compared to the general population analysis of US cancer registry data shows; with higher risk for those diagnosed at younger adult ages. The risk of osteosarcoma is increased by 5.1 times following radiotherapy, but chondrosarcoma risk is not significantly elevated. Bone sarcoma risk in patients with prior adult radiotherapy increases with longer time since diagnosis of the first cancer, and younger age at radiotherapy; there is also some evidence the risk varies by site of the primary cancer (hence the site of the radiotherapy).
Atomic bomb survivors (who have lower overall levels of exposure than patients receiving radiotherapy) have around 7.5 times increased bone sarcoma risk per 1Gy exposure, a cohort study showed. Studies of radiotherapy at doses lower than 5Gy have generally found no increased bone sarcoma risk, but low sample sizes preclude firm conclusions.
IARC classifies radioiodines, including Iodine-131, as possible causes of bone tumours, based on limited evidence. Iodine-131 is a radioactive isotope which can be used to treat hyperthyroidism and some types of thyroid cancer.
Exposure to computed tomography (CT) scans during childhood or adolescence is not associated with an increased risk of bone tumours, a large cohort study showed.