Thyroid cancer is diagnosed at a younger age than most other malignancies and the incidence is higher in women than men.

“The only established modifiable risk factors for thyroid cancer are childhood exposure to ionizing radiation and obesity. Few in-utero and early life risk factors have so far been identified” says Bjørge, professor at Department of Global Public Health and Primary Care, University of Bergen.

Maternal hypothyroidism, hyperthyroidism, goiter, and benign thyroid neoplasms related to higher risk

The teamconducted a nested case-control study using nationwide registry data from four Nordic countries (Denmark, Finland, Norway, and Sweden). The study included 2,437 thyroid cancer cases and 24,362 matched controls aged 0-48 years during 1967-2015.

“Maternal benign thyroid conditions such as hypothyroidism, hyperthyroidism, goiter, and benign thyroid neoplasms were strongly associated with thyroid cancer risk in offspring. Also, high birth weight, congenital hypothyroidism, maternal history of diabetes, and maternal postpartum haemorrhage were associated with increased risk,” says Bjørge.

Motivation for further research

The study supports a link between in-utero exposures and an increased risk of thyroid cancer later in life.

“These findings should motivate additional research into early-life exposures that might cause thyroid cancer,” says Bjørge.