Hemithyroidectomy or Total-Thyroidectomy in 'Low-risk' Thyroid Cancers

This is a multi-centre, randomised, non-inferiority, phase III study in patients with low risk differentiated thyroid cancer.Patients will be identified via oncology multidisciplinary team meetings. There will be two sources of patients in the trial, with the same histological diagnoses and prognosis (i.e. recurrence risk):Group 1: Patients who have already had a HT for thyroid problems and are then subsequently diagnosed with low risk DTC will be randomised 1:1 to undergo surveillance only OR a second operation to remove the rest of their thyroid gland (two-stage total thyroidectomy).Group 2: Patients diagnosed with low risk DTC using cytology (Thy5) but no surgery performed will be randomised 1:1 to have either a hemi-thyroidectomy OR a single-stage total thyroidectomy.The overall aim of the trial is to determine whether hemithyroidectomy is an acceptable and cost-effective surgical procedure compared to total thyroidectomy in low risk thyroid cancer. Overall, 456 patients will be recruited to the trial. Patients will be initially be followed up post-surgery then 12 monthly for 6 years.

Group 1 (HT already performed prior to diagnosis)Inclusion criteria• Aged 16 or overPapillary thyroid cancer:pT1b-2 (≤4cm) irrespective of molecular genetic markersR0 resection (clinically excised but microscopic R1 resected tumours at discretion of the local MDT)cN0 or pN0, pNX & pN1a (≤5 foci, no extranodal spread)Confined to thyroid or minimal extrathyroidal extensionNo higher risk histological variants on morphology (small foci allowed at the discretion of the local MDT)No angioinvasionEncapsulated FVPTC with capsular invasion onlyMicro-PTC (≤1cm)multifocalunifocal with pN1a (≤5 foci; no extranodal spread)Follicular thyroid cancer (FTC), including oncocytic or Hürthle cell carcinoma:pT1b-2 (≤4cm) irrespective of molecular genetic markers- Minimally invasive, with capsular invasion +/- minimal (≤4 foci) vascular invasion (the latter is now called encapsulated angioinvasive and is at the discretion of the MDT)Confined to thyroid or minimal extrathyroidal extensionExclusion criteria>4cmunifocal pT1a (≤1cm) PTC or FTC (unless pN1a as above)non-invasive encapsulated FVPTCAnaplastic, poorly differentiated or medullary thyroid carcinomaR2gross extrathyroidal extensionpT4 or macroscopic tumour invasion of loco-regional tissues or structurespN1a with >5 foci or extranodal spreadpN1bM1Aggressive PTC with any of the following features:Widely invasivePoorly differentiatedAnaplasticpredominance of Tall cell, Columnar cell, Hobnail, Diffuse sclerosing and other higher risk variantsFTC, including oncocytic or Hürthle cell cancer with any of the following features:Minimally invasive with extensive vascular invasion (now called encapsulated angioinvasive) (>4 foci)Widely invasivePoorly differentiatedAnaplasticGroup 2 (DTC on cytology or after core biopsy, who has not had prior thyroid surgery yet)Inclusion criteriaAged 16 or over'low risk' differentiated thyroid cancer confirmed by cytology or core biopsy.cT1b-2 irrespective of molecular genetic markerscN0Contralateral lobe without suspicious nodule(s) (U2, or U3/U4 with Thy2 on FNAC)Exclusion criteria• M1