Radioactivity and thyroid cancer.

There is no evidence that natural radiation (cosmic radiation or from natural radioiosotopes) increases the risk for thyroid diseases. Moreover, while it has been proven that exposure to external medical radiation or to external and internal radiation by atomic bomb explosions leads to an increased risk for thyroid cancer, the medical use of radioiodine, namely diagnostic and therapeutic application of (1)(3)(1)I, is safe and does not induce thyroid cancer. Exposure of children aged less than 4 years to fallout from the Chernobyl reactor accident has led to a substantial increase of childhood cancer incidence in the countries affected (Belarus, Ukraine and Western parts of Russia). Up to now, the total number of cases in children and adolescents adds up to approximately 5,000; in the next 50 years, approximately 15,000 additional thyroid cancer cases in this age group are expected. With respect to the Chernobyl effects on adults, there is no proven radiation related increase of the thyroid cancer incidence. As can be proven by a therapy project in 247 children with advanced thyroid cancer from Belarus, the prognosis for this tumor, even when metastasized, is good, this being in accordance with literature data indicating mortality rates between 1 and 2%.