It is generally estimated that 5 % of patients with thyroid cancer will develop distant metastases, and most of them had an advanced stage of the disease at presentation. Thirty per cent of them are resistant to radio iodine therapy and are called "refractory". Their long term survival is estimated to be less than 10 %.

The objective of this study is to identify the factors associated with poor outcome in a cohort of patients with advanced thyroid cancer followed during 5 years. Anaplastic and medullary thyroid carcinomas were excluded.

Inclusion Criteria:

• Man or woman ≥ 18 years.
• Thyroid cancer differentiated from follicular origins (papillary, vesicular or poorly differentiated carcinoma).
• TNM classification: stage pT3 (≥2 cm), or pT4 or M1 at diagnosis.
• Patient after post operative radioiodine therapy.

Exclusion Criteria:

• Patient who can not be followed during the protocol.
• Patient who does not consent.