 This study is being conducted to fulfil the specific obligation post-authorisation measure for the conditional marketing authorisation. It is carried on to confirm in real life conditions the benefitrisk of vandetanib CAPRELSATM 300 mg, both in RET negative and RET positive patients with symptomatic, aggressive, sporadic, unresectable, locally advancedmetastatic MTC. The clinical benefit of vandetanib CAPRELSATM 300 mg has previously been established in a clinical trial Study 58 on the basis of a clinically and statistically significant advantage in progression free survival PFS which was supported by a high response rate and substantial duration of response. 