Thyroid dysfunction and survival in cancer patients treated with immune checkpoint inhibitors: analyses from a large single tertiary cancer center database.

PURPOSE: We aimed to assess the incidence, clinical and biochemical course of immunotherapy-induced thyroiditis and its implication on patients' survival, based on an extensive clinical experience from a tertiary cancer center. METHODS: Analyses were based on data from the electronic medical records of cancer patients treated with CPIs. Data included demographic characteristics, cancer type, Thyroid function tests (TFT), and survival. RESULTS: Thyroid function tests were available for 934 patients. After excluding patients with impaired baseline TFT or levothyroxine treatment, 754 euthyroid patients were included in the core analyses. Of those, 301 (39.9%) patients developed thyroid dysfunction ('thyroiditis'). Thyroiditis was more prevalent in patients with renal cell carcinoma than other types of cancer. Survival rates were comparable in patients who developed thyroiditis and in those who did not. during the 5 years follow-up period, there was a non-significant trend toward improved survival in patients who developed TD in four predefined groups: melanoma, lung cancer, renal cell carcinoma, and transitional cell carcinoma. Nevertheless, we observed a highly significant survival benefit for patients with renal cell carcinoma who developed TD (HR = 0.19, 95% CI 0.06-0.60; p = 0.005). CONCLUSIONS: Thyroiditis is common, often asymptomatic, and is more prevalent in patients treated with combinations of nivolumab and PD-L1 inhibitors, and in patients with renal cell carcinoma. Thyroiditis was associated with a trend for a survival benefit, particularly in patients with renal cell carcinoma.