Incidence and clinical characteristics of thyroid abnormalities in cancer patients treated with immune checkpoint inhibitors

Introduction: Immune checkpoint inhibitors (ICI) are a group of drugs that have been used in recent years for the treatment of advanced malignancies such as melanoma, non-small cell lung cancer and other tumors, significantly increasing survival. However, the use of ICI has been associated with an increased risk of autoimmune diseases, with endocrine organs, specifically the thyroid, being highly susceptible to this phenomenon. Objective: To describe the incidence and clinical characteristics of patients treated with ICI who develop thyroid disease. Methods: The medical records of all patients who received ICI treatment within the last three years were retrospectively reviewed, with those who developed thyroid abnormalities being identified. Results: The prevalence of thyroiditis was 7 %, with an incidence of 21.4 % of patients-month. Median time for the development of thyroiditis was 63 days. Most patients had mild or moderate symptoms and did not require hospitalization, although all but one developed permanent hypothyroidism and required hormone replacement therapy with levothyroxine. Conclusions: Thyroid dysfunction secondary to immunotherapy is a common entity in our population. Clinical presentation is usually mild and does not require treatment discontinuation; however, due to the high incidence of these adverse events, non-oncology specialists must be familiar with the diagnosis and treatment of these alterations in order to provide multidisciplinary management.