Endocrine Abstracts

Immune checkpoint inhibitors (ICIs) have transformed cancer therapy across a broad range of malignancies. However, by enhacing T-cell-mediated immune responses, they may induce immune-related adverse events (IRAEs), with thyroid dysfunction being the most common endocrine toxicity. This audit aimed to assess the incidence, timing and management of thyroid dysfunction following immunotherapy, and to evaluate implications for future endocrine service provision. A retrospective review was conducted of all patients who received ICIs at St. James’s Hospital between July and December 2022. Data collected included cancer and immunotherapy type, thyroid function test (TFT) abnormalities, dates of onset and resolution, and whether levothyroxine was initiated. Management was assessed against European Society of Endocrinology guidelines. Q 4 2024 prescribing data was then used to more accurately estimate future impact, given the exponential growth of ICI use since 2022. Among 96 patients audited, 10.4% developed thyroiditis (median onset 31 days, resolution 35 days), 9.4% developed hypothyroidism without preceding thyroiditis (median onset 105 days), and 47.9% had other TFT derangements. 81.8% of patients commenced on levothyroxine were managed in accordance with the guidelines. Based on recent prescribing data, approximately 412 patients are expected to receive immunotherapy between July and December 2025. Applying audit rates, an estimated 43 would develop thyroiditis, 39 hypothyroidism, and 197 would have TFT derangements requiring clinical interpretation. These findings highlight the need for proactive monitoring and enhanced endocrine-oncology collaboration to ensure appropriate management and follow-up of affected patients.