Tyrosine kinase inhibitors and thyroid
The use of targeted therapies such as Tyrosine kinase inhibitors is becoming a common strategy in several advanced cancers. Several tyrosine kinases are targeted by the drugs, and the anti-neoplastic actions involves both anti-proliferative and anti-angiogenesis effects. Initial case reports, have been followed by series reporting treatment induced thyroid dysfunctions. They include thyrotoxicosis and hypothyroidism sometimes with a biphasic course, reminiscent of silent subacute thyroiditis, in previously euthyoid patients. In addition, in treated hypothyroid patients, these drugs may jeopardize the maintenance of euthyroidism by the thyroxine treatment, as well as the TSH suppression in the case of thyroid differentiated cancer. The mechanisms of the thyroid dysfunctions are not fully elucidated up to now and they may be differences in the mechanisms involved between the different drugs. Thyroid dysfunction should be screened for in patients on tyrosine kinase inhibitors since well-being and quality of life may be severely affected.