Fetal growth and subsequent maternal risk of thyroid cancer

Abstract

Thyroid cancer has peak incidence among women of reproductive age, and growth factors, which have procarcinogenic properties, may play an important etiologic role. However, the association between fetal growth rate during a woman’s pregnancy and her subsequent risk of thyroid cancer has not been previously examined. We conducted a national cohort study of 1,837,634 mothers who had a total of 3,588,497 live-births in Sweden in 1973-2008, followed up for thyroid cancer incidence through 2009. There were 2,202 mothers subsequently diagnosed with thyroid cancer in 36.8 million person-years of follow-up. After adjusting for maternal age, height, weight, smoking, and sociodemographic factors, high fetal growth (birth weight standardized for gestational age and sex) was associated with a subsequent increased risk of thyroid cancer in the mother (incidence rate ratio [IRR] per additional 1 standard deviation, 1.05; 95% CI, 1.01-1.09; P=0.02). Each 1,000 g increase in the infant’s birth weight was associated with a 13% increase in the mother’s subsequent risk of thyroid cancer (IRR, 1.13; 95% CI, 1.05-1.22; P=0.001). These findings appeared to involve both papillary and follicular subtypes, and did not vary significantly by the mother’s height, weight, or smoking status. In this large national cohort study, high fetal growth during a woman’s pregnancy was independently associated with a subsequent increased risk of her developing thyroid cancer. If confirmed, these findings suggest an important role of maternal growth factors in the development of thyroid cancer, and potentially may help facilitate the identification of high-risk subgroups of women.

The role of pregnancy, perinatal factors and hormones in maternal cancer risk: a review of the evidence

“…Other placental hormones and growth factors that are increased during pregnancy may also contribute to thyroid cancer development. For instance, findings from a recent Swedish study showing an increased risk of maternal thyroid cancer associated with higher foetal growth and birthweight, support a possible role of placental IGF‐I . A history of infertility and use of fertility drugs have been associated with thyroid cancer risk in some studies , albeit not entirely consistently .…”

The role of pregnancy in maternal cancer risk: Epidemiologic evidence from the Nordic Countries Linked Birth and Cancer Registries Cohort Project

“…Diagnosis of hyperemesis gravidarum has been associated with increased risk of maternal thyroid cancer (67). Higher fetal growth and birth weight also have been associated with an increased risk of maternal thyroid cancer (68), while longer duration of breastfeeding has been associated with a modest reduction in risk (65,69). It is not clear whether any or all of these findings are confounded by healthcare access or thyroid cancer screening, leading to the identification and diagnosis of subclinical thyroid cancers (63).…”

Association between excessive fetal growth and maternal cancer in Shanghai, China: a large, population-based cohort study

“…3 However, other studies have shown that excessive fetal growth is associated with an increased risk of developing hormone-related cancers in mothers, such as breast, thyroid and ovarian cancer. [4][5][6] Moreover, a large cohort study in Sweden found that excessive fetal growth was independently associated with a higher risk of colorectal cancer. 7 The potential etiology of the different types of cancer may be the different in uences of rapidly increasing levels of estrogen, progesterone, insulin-like growth factor-1 (IGF-1), and leptin during pregnancy.…”