Does Thyroxine Tx in Hypothyroidism Cause Thyroid Cancer?

HealthDay News — Patients with primary hypothyroidism who are regular thyroxine users have increased risk of thyroid cancer, according to a study published online in the Journal of Clinical Pharmacology.

Shih-Han Hung, MD, from Taipei Medical University Hospital in Taiwan, and colleagues conducted a case-control study to examine the correlation of thyroid cancer with primary hypothyroidism using data from the Taiwan Longitudinal Health Insurance Database 2005. Data were included for 1285 patients with cancer and 3855 sex- and age-matched controls.

The researchers identified a prior hypothyroidism diagnosis in 2.88% of cases and 0.86% of controls. Compared with controls, cases were more likely to have been previously diagnosed with hypothyroidism (adjusted odds ratio [aOR], 3.01). There was a significant association for thyroid cancer with hypothyroidism patients who were regular thyroxine users (aOR, 8.68). For hypothyroidism patients who were irregular thyroxine users, there was no significant association with thyroid cancer.

“Additional studies are needed to further evaluate and validate these findings,” the authors write.

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Hung S-H, Chung S-D, Lin H-C. Thyroxin use is associated with increased risk of thyroid cancer in patients with hypothyroidism [published online July 19, 2017]. J Clin Pharmacol. doi:10.1002/jcph.972