Yttrium-90 transarterial radioembolization for liver metastases from medullary thyroid cancer

Objectives: Liver metastases occur in 45% of patients with advanced metastatic medullary thyroid cancer (MTC). Transarterial radioembolization (TARE) has been proposed to treat liver metastases (LM), especially in neuroendocrine tumors. Aim of this study was to investigate the biochemical (calcitonin and CEA) and objective response of liver metastases from MTC to TARE. Methods: TARE is an internal radiotherapy in which microspheres loaded with β-emitting yttrium-90 (90Y) are delivered into the hepatic arteries that supply blood to LM. Eight patients with progressive multiple LM underwent TARE and were followed prospectively. They were clinically, biochemically and radiologically evaluated at 1, 4, 12 and 18 months after TARE. Results: Two patients were excluded from the analysis for severe liver injury and for death due to extrahepatic disease progression, respectively. One month after TARE a statistically significant (p=0.02) reduction of calcitonin was observed in all patients and remained clinically relevant during follow-up; reduction of CEA, although not significant, was found in all patients. Significant reduction of liver tumor mass was observed 1, 4 and 12 months after TARE (p=0.007, p=0.004, p=0.002, respectively). After 1 month, 3/6 patients showed partial response (PR) and 3/6 stable disease (SD) according to RECIST 1.1, while 5/6 patients had a PR and 1/6 a SD according to mRECIST. The clinical response remained relevant 18 months after TARE. Excluding one patient, all others showed only a slight and transient increase of liver enzymes. Conclusions: TARE is effective in LM treatment of MTC. The absence of severe complications and the good tolerability makes TARE a valid therapeutic strategy when liver LM are multiple and progressive.