The incidence and perinatal outcomes of pregnancy-associated thyroid cancer: an Australian population-based study.

OBJECTIVE

To describe the incidence and perinatal outcomes of pregnancy-associated thyroid cancer (PATC).

DESIGN

A population-based, retrospective data linkage cohort study.

SETTING

New South Wales (NSW), Australia.

POPULATION: Women giving birth in NSW between 1994 and 2013. Women were stratified into a PATC group (women diagnosed with thyroid cancer during pregnancy (gestational) or within 1 year postpartum) or a non-cancer pregnant control group.

MAIN OUTCOME MEASURES: Pregnancy, maternal and perinatal outcomes, time to next birth, and thyroid cancer incidence and management.

RESULTS

Three hundred and seventy of 1 788 451 women giving birth during the study period were diagnosed with PATC (incidence rate = 20.7/100 000 women giving birth; annual increase adjusted for maternal age = 5.0% (95% CI: 3.1%-6.9%)). Sixty-two women had gestational thyroid cancer and 308 had postpartum thyroid cancers. Twenty-seven (43.5%) women with gestational thyroid cancer had a subsequent birth. Treatment data were available for 41 women with gestational thyroid cancer. Thirty-two (78.0%) underwent a thyroidectomy during pregnancy, while 6 deferred thyroid surgery until postpartum. Radioactive iodine was administered to 24 (58.5%) of these women postpartum. Women with postpartum thyroid cancer had increased odds of gestational diabetes (adjusted odds ratio: 1.59, 95% CI 1.09-2.32; adjusted for the covariates available within the dataset).

CONCLUSION

The rising incidence of PATC over the study period mirrored an increase in the general population. Most women with gestational thyroid cancer had antepartum surgical management followed by postpartum radioactive iodine with favorable outcomes for the women and their babies.