Women’s thyroid cancer risk may be linked to reproductive lifespan and hormone therapy

Longer lifetime exposure to female hormones may increase thyroid cancer risk in women, according to research presented Saturday at the ENDO 2026 meeting in Chicago, Ill. Scientists from The Catholic University of Korea found that longer reproductive spans and extended hormone replacement therapy (HRT) are linked to a higher incidence of the disease.

Why is thyroid cancer more common in women?

Thyroid cancer occurs more frequently in women than in men, though the specific causes for this disparity remained unknown until this research. Scientists from the College of Medicine at The Catholic University of Korea in Seoul sought to identify these drivers through a population-based study.

The researchers analyzed data from approximately 5.7 million women aged 40 years or older. This data came from the Korean National Health Insurance Service, the nation’s universal health coverage program.

How do reproductive factors affect cancer risk?

The study found that about 2.4 out of every 1,000 people develop thyroid cancer annually. A longer reproductive span was linked to a progressively increased risk of the disease, according to the findings.

Hormone replacement therapy (HRT) also showed a correlation with increased risk. This association was stronger in women who used HRT for five years or more.

To ensure accuracy, the team used Cox proportional hazards regression models. They adjusted for variables including age, smoking, alcohol use, physical activity, BMI, hypertension, diabetes, dyslipidemia, household income, and previous cancer history.

What are the implications for women’s health?

The research suggests that reproductive and hormonal factors are likely involved in thyroid carcinogenesis. This means common life events, such as the timing of menopause, may influence a woman’s risk profile.

“A woman’s reproductive history could be considered in assessing her individual risk to developing thyroid cancer,” said Jinyoung Kim, M.D. Ph.D., assistant professor in the College of Medicine at The Catholic University of Korea.

What may happen next in thyroid research?

Medical professionals may start incorporating reproductive history into standard thyroid cancer risk assessments. This could lead to more personalized screening schedules for women with longer reproductive spans or extensive HRT use.

Further research may be likely to explore the specific biological mechanisms that link female hormones to thyroid carcinogenesis to determine why these factors increase risk.

Frequently Asked Questions

Who conducted the research on thyroid cancer risk?
Scientists from the College of Medicine at The Catholic University of Korea in Seoul conducted the study.

Which specific hormonal factors were linked to increased risk?
The study identified a longer reproductive span and the use of hormone replacement therapy (HRT), particularly for five years or more, as factors associated with increased risk.

How large was the study population?
The nationwide population-based study included approximately 5.7 million women aged 40 years or older.

How do you think personalized health screenings based on reproductive history might change preventative care?