Maternal health, in-utero, and perinatal exposures and risk of thyroid cancer in offspring: a Nordic population-based nested case-control study

Summary Background Thyroid cancer tends to be diagnosed at a younger age (median age 51 years) compared with most other malignancies (such as breast cancer [62 years] or lung cancer [71 years]). The incidence of thyroid cancer is higher in women than men diagnosed from early adolescence. However, few in-utero and early life risk exposures associated with increased risk of thyroid cancer have been identified. Methods In this population-based nested case-control study we used registry data from four Nordic countries to assess thyroid cancer risk in offspring in relation to maternal medical history, pregnancy complications, and birth characteristics. Patient with thyroid cancer (cases) were individuals born and subsequently diagnosed with first primary thyroid cancer from 1973 to 2013 in Denmark, 1987 to 2014 in Finland, 1967 to 2015 in Norway, or 1973 to 2014 in Sweden. Each case was matched with up to ten individuals without thyroid cancer (controls) based on birth year, sex, country, and county of birth. Cases and matched controls with a previous diagnosis of any cancer, other than non-melanoma skin cancer, at the time of thyroid cancer diagnosis were excluded. Cases and matched controls had to reside in the country of birth at the time of thyroid cancer diagnosis. Conditional logistic regression models were used to calculate odds ratios (ORs) with 95% CIs. Results Of the 2437 cases, 1967 (81·4%) had papillary carcinomas, 1880 (77·1%) were women, and 1384 (56·7%) were diagnosed before age 30 years (range 0–48). Higher birth weight (OR per kg 1·14 [95% CI 1·05–1·23]) and congenital hypothyroidism (4·55 [1·58–13·08]); maternal diabetes before pregnancy (OR 1·69 [0·98–2·93]) and postpartum haemorrhage (OR 1·28 [1·06–1·55]); and (from registry data in Denmark) maternal hypothyroidism (18·12 [10·52–31·20]), hyperthyroidism (11·91 [6·77–20·94]), goiter (67·36 [39·89–113·76]), and benign thyroid neoplasms (22·50 [6·93–73·06]) were each associated with an increased risk of thyroid cancer in offspring. Interpretation In-utero exposures, particularly those related to maternal thyroid disorders, might have a long-term influence on thyroid cancer risk in offspring. Funding Intramural Research Program of the National Cancer Institute (National Institutes of Health).