Part of “CHAPTER 39 – THE THYROID NODULE“

Many causative factors in the development of thyroid nodules, especially thyroid carcinomas, are uncertain. One undisputed factor, however, is radiation exposure. Animal studies have consistently confirmed radiation induction of thyroid neoplasia, which can be further promoted by TSH. By 1950, many children with thyroid carcinoma were known previously to have received radiation to the neck as treatment for benign conditions, including enlarged thymus, chronic tonsillitis, acne, and cervical adenitis. Numerous studies have now confirmed a linear relationship between radiation dose (for doses up to 1500 rad) and the incidence of thyroid nodules and thyroid cancer.

Some 40 million Ci of iodine-131 (¹³¹I) and another 100 million Ci of shorter-lived isotopes of iodine were released into the atmosphere by the nuclear reactor accident at Chernobyl in the Belarus in April 1986. The number of new cases of thyroid cancer appearing in patients who were exposed to the fallout as young children in 1986 has shown a dramatic increase between 1989 and the present.34,35 Similar associations were demonstrated for radioactive fallout after the World War II experience in Japan and the atomic test explosions in the Marshall Islands. Nasopharyngeal radium implants appear to add little risk of cancer.