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Benign Thyroid Conditions Associated with Increased Risk of Thyroid Cancer Later in Life

Posted on April 05, 2018

Anatomy of the thyroid, Terese Winslow (Illustrator)

In a new study from the National Cancer Institute and Aarhus University Hospital in Denmark, researchers report an association between diagnosis of hyperthyroidism and thyroiditis (inflammation of the thyroid gland), two benign thyroid conditions, and increased risk of differentiated thyroid cancer. The study was published online March 23, 2018, in the Journal of Clinical Endocrinology and Metabolism.

Previous epidemiologic studies have found that certain benign thyroid conditions, such as benign thyroid nodules, adenoma (a benign tumor), and goiter (swelling in the neck resulting from an enlarged thyroid gland) are associated with thyroid cancer risk. However, there was little evidence as to whether thyroid dysfunction and thyroid autoimmunity influence risk.

Cari Kitahara, Ph.D., and colleagues prospectively examined a wide range of benign thyroid conditions and risk of differentiated thyroid cancer using data for the period 1978-2013 from nationwide hospital and cancer registries in Denmark. They found an unexpected increased risk of differentiated thyroid cancer, including regional/distant disease, following diagnosis of hyperthyroidism and thyroiditis that could not be solely attributed to increased medical surveillance. Patients diagnosed with goiter and adenoma also had an increased risk of differentiated thyroid cancer, while hypothyroidism was less clearly associated with thyroid cancer risk.

This work provides important new evidence on risk factors for thyroid cancer. While the results support a possible role of thyroid dysfunction and autoimmunity in thyroid cancer development, further investigation is needed to better understand the underlying biological mechanisms.

Reference: Kitahara CM, et al. Benign thyroid diseases and risk of thyroid cancer: A nationwide cohort study. J Clin Endocrinol Metab. March 23, 2018. https://doi.org/10.1210/jc.2017-02599.