Tyrosine kinase inhibitor-induced hypothyroidism: incidence, etiology, and management

In recent years, tyrosine kinase inhibitors (TKIs) have emerged as a new class of anti-cancer therapy with proven efficacy in several types of carcinoma. Although generally considered less toxic than cytotoxic chemotherapy, TKIs do have significant side effects including fatigue and hypertension. In addition, TKI-induced thyroid dysfunction is now recognized as a common toxicity that is associated with some TKI inhibitors. Detection of TKI-induced thyroid dysfunction requires routine monitoring of thyroid function and, in some cases, may require treatment. This review provides a comprehensive assessment of literature evaluating TKI-induced thyroid dysfunction, focusing on the potential mechanisms that result in this toxicity, whether the development of thyroid dysfunction is clinically meaningful, and controversies regarding treatment with thyroid hormone therapy.