Abstract
Background: Immune checkpoint inhibitors (ICIs) have significantly improved clinical outcomes in patients with advanced malignancies. However, their use is associated with immune-related adverse events (irAEs), among which thyroid dysfunction is the most common endocrine complication.
Objective: Еvaluate the incidence and clinical characteristics of ICI-induced thyroid dysfunction in patients treated at a tertiary oncology centre.
Methods: This retrospective observational cohort study included 341 patients with histologically confirmed lung cancer or malignant melanoma who received ICI therapy between January 2024 and January 2025. Clinical data, treatment characteristics, history of thyroid disease, and thyroid function test results were retrieved from the hospital information system. Screening, diagnosis, and management of thyroid dysfunction were performed in accordance with the recommendations of the European Society of Endocrinology (ESE), the European Society for Medical Oncology (ESMO), and the National Comprehensive Cancer Network (NCCN).
Results: Thyroid dysfunction developed in 9% of patients receiving ICIs. Hypothyroidism was the predominant manifestation, accounting for 87% of all thyroid dysfunction cases, whereas transient thyrotoxicosis occurred in 13%. Pembrolizumab was the ICI most frequently associated with thyroid dysfunction. Levothyroxine replacement therapy was initiated in 89% of patients with hypothyroidism. The mean time to diagnosis of hypothyroidism was 6.5 weeks after initiation of ICI therapy.
Conclusions: ICI-induced thyroid dysfunction is one of the most common irAEs and typically develops during the early phase of treatment. Regular monitoring of thyroid function facilitates early diagnosis and appropriate management, thereby supporting the continuation of oncological treatment while minimizing endocrine complications.