Endocrine Abstracts

Tyrosine kinase inhibitors (TKIs) are relatively new therapy drugs used for the treatment of metastatic cancers including Renal cell carcinoma (RCC), gastrointestinal stromal tumours, thyroid and neuroendocrine tumours. They block vascular endothelial growth factor and other growth factors Thyroid dysfunction is often a side effect of this treatment. A close monitoring of thyroid hormone levels is a necessity.

We have a case of a 69-year-old lady with RCC diagnosed in 2001 and she was treated with three different types of TKIs: Sunitinib (2010–2012), Pazopanib (2012–2016) and Axitinib (2016). She developed hypothyroidism in 2010 was started on replacement treatment. Despite no changes in the dose she developed profound clinical and biochemical hypothyroidism after (TSH 26 mU/l and normal T4 15 pmol/l) after initiation of Axitinib. Her symptoms included tiredness and hair thinning and body aches.

This was initially picked up by the biochemistry department and was later communicated to the oncologists by the endocrinologists through MDT discussion. And her thyroxine dose was increased.

Discussion: This case illustrates the lack of awareness among clinicians about the significance of thyroid dysfunction related to TKI despite this being common. Also we could prove different degrees of thyroid dysfunction with different TKIs in the same patient, Axitinib being the potent agent followed by Sunitinib and Pazopanib. The research evidence in this area is scarce and there are no National guidelines about how to treat this. Also a MDT approach is required as in this case to improve the patient outcome.