Biomarker testing in patients diagnosed with advanced/metastatic medullary thyroid cancer in the USA.

Mutations in the RET gene are common in patients with medullary thyroid cancer (MTC). As RET mutations are involved in the development of MTC, several treatment guidelines recommend counseling patients and testing for mutations in the RET gene in all patients with MTC. However, limited data are available on RET testing patterns in the USA in this patient population. In this study, the authors determined testing patterns for RET in patients with advanced or metastatic MTC in the USA using real-world data and found that only 60% of patients were tested for RET (i.e., testing for presence of RET mutations was observed in less than two-thirds of all patients included in the study). These results demonstrate the need for improved testing for RET mutations in patients with MTC in alignment with the treatment guidelines in routine clinical practice in the USA.