Endocrine Abstracts

Background: We analyzed the role of imaging in the identification of medullary thyroid carcinoma (MTC) metastases and in the assessment of treatment response of the patients in clinical trials and research studies devoted to MTC.

Materials and methods: A search for published studies devoted to MTC from January 2010 to August 2017 was performed.

Results: Fifteen studies published in peer review journals that evaluated the effects of sorafenib, cabozanitinib, vandetanib and sunatenib were analyzed. In a pooled cohort of 922 patients with advanced MTC, metastases in lymph nodes were found in 70%, liver in 63%, lungs in 54% and bone in 44%. Eleven out of 15 publications described imaging modalities to assess metastases. Of those, all 11 reported the use of computed tomography (CT), five used magnetic resonance tomography (MRI), in two studies bone scintigraphy. Only one study reported the exploratory use of positron emission tomography/computed tomography (PET/CT) with 18-fluorodeoxyglucose and dynamic contrast-enhanced MRI. No study used PET/CT with fluorine-18-dihydroxyphenylalanine (18-F-DOPA). Imaging timing for initial and follow-up varied. All studies used Response Evaluation Criteria In Solid Tumors (RECIST) to assess the response to treatment. Cumulative analysis showed that overall complete response was diagnosed only in one case (0.3%); partial response in 30%, stable disease was noted in 60% and progressive disease in 10% without statistical significance between the studies and types of treatment used. A meta-analysis showed the limited use of modern imaging modalities for MTC and the lack of detailed description of radiological findings in all analyzed publications. There is no consensus and protocol on the radiological evaluation of MTC patients. New advanced imaging techniques (such as diffusion-weighted MRI, dynamic contrast MRI, PET/CT with 18-F-DOPA, 69-GA DOTATATE etc), which have high diagnostic value in oncology, were not used in presented studies.

Conclusion: 1. Modern imaging modalities have limited use in clinical research and trials devoted to MTC.

2. Development and introduction of new imaging protocols will be very helpful for further research of new treatment modalities and comparison of the efficiency of different treatments.

3. New advanced imaging techniques may be helpful in advanced MTC and therefore should be evaluated.

4. RECIST does not adequately reflect changes related to treatment in MTC, therefore it should not use in the future.