Endocrine Abstracts

Introduction: With the advent of specific gene targeted therapies for advanced thyroid cancers it has become important that molecular genetic testing is requested to identify patients suitable for these treatments, for example with BRAF, RET or NTRK inhibitors. We investigated the proportion of patients with advanced thyroid cancer in a specialist thyroid cancer clinic who had undergone appropriate testing.

Participants and Methods: 56 patients with advanced thyroid cancer were identified from clinic records. Patients were divided by histological subtype, with 36 differentiated (DTCs), 16 medullary (MTCs), and 3 anaplastic (ATCs) cancers, as well as one NUT carcinoma initially thought to be DTC. Patients were excluded if they had extensive comorbidities (1) or were responding to conventional treatments (12). For the remaining 43 patients (24 DTCs, 15 MTCs, 3 ATCs, and 1 NUT carcinoma), records were checked for molecular testing.

Results and discussion: The majority (86.0%) of patients had undergone genetic testing. This included the NUT carcinoma and all ATC patients, compared to 20 (83.3%) of DTC and 13 (86.7%) of MTC patients. Of those eligible and tested, 20.0% of DTC patients had a genetic mutation identified, compared to 84.6% of MTC patients. Whilst this difference is not unexpected, a particularly high rate of MTC patients with RET mutations is explained by the clinic being a referral centre for a clinical trial of a RET specific therapy. Whilst most patients had had the appropriate testing, a small number were identified who needed this to be requested, to allow identification of treatment options.

Conclusion: Genetic testing is essential to identify patients suitable for targeted systemic therapies. These treatments can transform the patient’s quality of life and prolong their survival. Additionally, this project has shown genetic testing helps identify rarer subtypes, such as NUT carcinoma.