Endocrine Abstracts

Medullar Thyroid cancer (MTC) is uncommon and a mixture of sporadic and familial. Surgery is the only curative treatment to date. Prophylactic surgery is required in the hereditary forms. No adjuvant post-operative treatment has demonstrated survival benefit. External radiotherapy may be used selectively. Calcitonin and CEA are used for post-operative monitoring of recurrence. At time of relapse consider whether there is a surgical option. The rate of doubling has prognostic value and helps to determine timing of intervention. Traditional chemotherapy is of very limited use. New targeted agents have shown considerable activity. Vandetanib and cabozantinib are the two approved agents. Specific RET antagonists are showing greater potential benefit Metastatic MTC is often very slow growing and indolent so do not rush in with systemic therapies. Patients should be managed by specialist teams with access to a CNS.

Synopsis of talk: Medullary thyroid cancer: management challenges

Medullary thyroid cancer (MTC) is uncommon and accounts for between 5 and 10% of all thyroid cancers. MTC may be hereditary as in MEN2 and FTC but there are sporadic forms although new technology identified. In familial forms prophylactic surgery is deployed. Patients are either diagnosed through genetic screening or present with a thyroid lump. Surgery is the only curative treatment to date. Selective use of adjuvant radiation may be considered for high risk cases such as positive margins and heavy nodal infiltrate. Post-operative monitoring is clinical and biochemical with measurement of CEA and Calcitonin. Many cases are indolent but monitoring the doubling time of Calcitonin gives prognostic information and helps to determine timing of intervention. When there is a relapse, determine if there is an opportunity to consider further surgical intervention. Many patients with metastatic disease have very slow growing metastases or may have negative imaging with elevated stable Calcitonin levels and these may be kept under surveillance for years. Intervention should only be considered for symptomatic progressive disease. Traditional chemotherapy has little value so the use of new targeted agents has developed rapidly. These are multi-targeted TKIs and the only two approved are vandetanib and cabozantinib although a number of others has shown clinical benefit. They appear to be of roughly equal efficacy so personal experience and familiarity with toxicities may determine which is used. New more specific ret pathway inhibitors (LOXO 292 and BLU 667) are reported to show significantly higher levels of activity and lower toxicity but have not progressed beyond phase 2 studies. Everolimus an mTOR pathway inhibitor may be of use, and radionuclide studies show some patients may benefit from PRRT using mIBG or Lutetium. Patients should be managed in specialist clinics with experience of managing MTC and with access to Clinical Nurse Specialists.