IoN- Is Ablative Radio-iodine Necessary for Low Risk Differentiated Thyroid Cancer Patients

TNM eligibility is assessed against TNM7 (7th edition 2009) or TNM8 (8th edition 2017, in use in the UK from 01/01/2018). Eligibility Criteria using TNM7: Inclusion criteria: * Histological confirmation of well differentiated thyroid carcinoma: MDT decision for inclusion based on overall clinico-pathological assessment is critical. * R0 total thyroidectomy (in one or two stages, no residual disease present; Rx at the discretion of the MDT) within the last 6 months * Negative pregnancy test in women of child bearing potential * Aged 16 or over * WHO performance status 0 - 2, self-caring * Histological confirmation of differentiated thyroid carcinoma:MDT decision for inclusion based on overall clinico-pathological assessment * Papillary thyroid cancer (PTC): * Non aggressive histological features (small foci of aggressive histology allowed at the discretion of the MDT) * pT1a (≤1cm) unifocal with positive level VI lymph nodes (pN1a) * pT1a(m): all individual foci ≤1cm * pT1b and pT1b(m): \>1-2cm * pT2 and pT2(m): \>2-4cm * pT3 and pT3(m): \>4cm confined to the thyroid * pT3 R0 +/- (m): any size with minimal ETE if recommended by the MDT * pN0 * pN1a * pNX * Follicular thyroid cancer (FTC) (including oncocytic or Hürthle cell cancer): o minimally invasive FTC -which are considered low risk and are recommended by the specialist MDT based on overall clinico-pathological assessment * pT1b and pT2: \>1-4cm intrathyroidal * pT3 R0:any size up to 4 cm wi…