Clinical Thyroidology® for the Public
Summaries for the Public from recent articles in Clinical Thyroidology
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THYROID CANCER
Thyroid cancer and autoimmune thyroid disease.
BACKGROUND
Autoimmune thyroid disease refers to a group of disorders in which a person makes antibodies that target the thyroid gland. Some people make stimulating antibodies (TSI) that turn on the thyroid and cause an overactive thyroid gland (Graves’ disease). More commonly, some people make destructive antibodies (TPO or anti-TG) that can destroy the thyroid and cause an underactive thyroid gland (Hashimoto’s thyroiditis). Research has suggested that there may be an association between autoimmune thyroid disease and thyroid cancers. Some studies have shown perhaps an increased risk of thyroid cancer in people with autoimmune thyroid disease but potentially better overall outcomes (less aggressive cancer). This has been a controversial topic in the thyroid research literature.
The aim of this study was to investigate the relationship between the presence of autoimmune thyroid disease and thyroid cancer patient outcomes at 1 year after treatment.
THE FULL ARTICLE TITLE
De Leo S, et al. A prospective multicenter study examining the relationship between thyroid cancer treatment outcomes and the presence of autoimmune thyroiditis. Thyroid. 2023;33(11):1318-1326; doi: 10.1089/thy.2023.0052. PMID: 37725571
SUMMARY OF THE STUDY
This is a study examining outcomes at 1 year following treatment for papillary or follicular thyroid cancer in patients with or without autoimmune thyroid disease. They included data from 4233 cancer patients who enrolled in the Italian Thyroid Cancer Observatory database and divided them into patients with or without autoimmune thyroid disease to compare outcomes at 1 year. Patients were considered to have autoimmune thyroid disease if they had an elevated TPO or TG antibody level and characteristics of autoimmunity on ultrasound or surgical pathology. All patients were classified at diagnosis as having an estimated risk of thyroid cancer persistence as low, intermediate, or high based on the American Thyroid Association guidelines.
Thyroid cancer status was evaluated at 1 year post initial treatment (which varied by patient risk). Patients were grouped into 4 categories: 1) no evidence of thyroid cancer 2) biochemical persistence (abnormal thyroglobulin tumor marker) 3) structural disease (imaging consistent with persistent or new evidence of cancer) and 4) Indeterminate status. Outcomes at 1 year were compared in thyroid cancer patients with and without autoimmune thyroid disease.
Thyroid cancer patients with autoimmune thyroid disease were younger than those without autoimmune thyroid disease. Further, they had smaller cancers that were more likely to be classified as low or intermediate risk categories at baseline. Overall, higher risk patients were less likely to have autoimmune thyroid disease. Thyroid cancer patients with autoimmune disease were more likely to have evidence of persistent biochemical disease (abnormal thyroglobulin) but were not at increased risk of persistent disease on imaging at 1 year.
WHAT ARE THE IMPLICATIONS OF THIS STUDY?
Overall, patients with thyroid cancer show an excellent response to treatment. Thyroid cancer patients without autoimmune thyroid disease were more likely to have higher risk cancers than patients with autoimmune thyroid disease. However, thyroid cancer patients with autoimmune thyroid disease may be at increased risk of persistent biochemical disease (positive thyroglobulin cancer marker) but are lower risk of having structurally persistent thyroid cancer at one year post treatment. As expected, patients with higher risk thyroid cancer at the time of diagnosis are more likely to have persistent disease at one year.
— Whitney W. Woodmansee MD
ATA RESOURCES
Thyroid Cancer (Papillary and Follicular): https://www.thyroid.org/thyroid-cancer/
Hashimoto’s Thyroiditis: https://www.thyroid.org/hashimotos-thyroiditis/
ABBREVIATIONS & DEFINITIONS
Autoimmune thyroid disease: a group of disorders that are caused by antibodies that get confused and attack the thyroid. These antibodies can either turn on the thyroid (Graves’ disease, hyperthyroidism) or turn it off (Hashimoto’s thyroiditis, hypothyroidism).
Hashimoto’s thyroiditis: the most common cause of hypothyroidism in the United States. It is caused by antibodies that attack the thyroid and destroy it.
Graves’ disease: the most common cause of hyperthyroidism in the United States. It is caused by antibodies that attack the thyroid and turn it on.
Thyroid stimulating immunoglobulin/TSI: antibodies often present in the serum of patients with Graves’ disease that are directed against the TSH receptor, that cause stimulation of this receptor resulting in increased levels of thyroid hormones in the blood and hyperthyroidism
TPO antibodies: these are antibodies that attack the thyroid instead of bacteria and viruses, they are a marker for autoimmune thyroid disease, which is the main underlying cause for hypothyroidism and hyperthyroidism in the United States.
Thyroglobulin antibodies: these are antibodies that attack the thyroid instead of bacteria and viruses, they are a marker for autoimmune thyroid disease, which is the main underlying cause for hypothyroidism and hyperthyroidism in the United States.
Thyroglobulin: a protein made only by thyroid cells, both normal and cancerous. When all normal thyroid tissue is destroyed after radioactive iodine therapy in patients with thyroid cancer, thyroglobulin can be used as a thyroid cancer marker in patients that do not have thyroglobulin antibodies.
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