Childhood exposure to ionising radiation is a well established risk factor for thyroid cancer with some studies suggesting that the risk of development increases with decreasing age at exposure.
A study using registry data from 4 Nordic countries (Denmark, Finland, Norway, and Sweden) compared 2,437 thyroid cases with 24,362 matched controls to investigate the role of intrauterine exposures on thyroid cancer development. They assessed the risk of thyroid cancer risk in offspring in relation to maternal medical history, pregnancy complications, and birth characteristics.
Researchers found that the risk of thyroid cancer in later life was associated with high birth weight, maternal pre-pregnancy diabetes, and postpartum haemorrhage. Exposure to maternal thyroid conditions such as hypo- and hyperthyroidism, goiter and benign thyroid neoplasms were also strong risk factors, supporting a potential role of iodine deficiency in thyroid cancer development. Most cases of thyroid cancer were papillary carcinomas and diagnosed in women younger than 30 years.
Why it matters: Few early life risk factors for thyroid cancer have been identified. The findings provide evidence for the association between in-utero exposures, and an increased risk of thyroid cancer in later life which may guide future research to identify modifiable risk factors and targets for the primary prevention of thyroid cancer.