Very low-risk papillary thyroid carcinoma: where to set the limits?

M Martinho; T Azevedo; T Martins; N Cunha; M J Rascao; C Oliveira; J Neto; S Oliveira; P Gilde; A Neves; I Gomes; C Cruz; F Valido; B Campos; F Rodrigues

Currently there is no widely accepted definition of very low-risk papillary thyroid carcinoma (PTC). Although unifocal microcarcinomas without extrathyroidal extension and no local or distant metastases have been recognized as having an excellent overall prognosis the threshold for such a favourable clinical behaviour remains controversial. The study aim was to identify the clinicopathological characteristics of T1 tumours (≤2 cm) presenting a very low-risk of mortality or recurrence. We retrospectively reviewed the medical data of 258 patients with PTC presenting the following characteristics: T1N0M0 disease, no history of head-neck irradiation, all macroscopic tumour had been resected and the tumour did not have aggressive histological subtype. Periodic follow-up included clinical and ultrasound examination and serum Tg, TSH and antithyroglobulin antibodies measurements. Other imaging modalities were used as required. There were 226 (87.6%) female patients. Mean age at diagnosis was 48.0 years (range, 22–79 years). One hundred ten patients were classified as T1b. The majority of the patients (93.4%) were treated with total or near-total thyroidectomy. Forty-nine patients (18.9%) underwent a variety of cervical lymph node dissections. Radioiodine ablation therapy was administered to 111 patients (43.0%). Patients were followed for a median of 8.2 years after thyroidectomy. Residual/recurrent disease in regional lymph nodes was identified in six patients (2.3%). There was no disease-specific mortality and none of the patients developed distant metastases during follow-up. All patients were considered free of disease at the last follow-up. This study shows that it is possible with a simple set of criteria to accurately identify a subgroup of T1N0M0 PTC patients with very low-risk of recurrence. Our results may suggest that these very low-risk patients may be effectively treated with a conservative management strategy in terms of surgical treatment (extent of thyroidectomy and prophylactic lymph node dissections), radioiodine ablation therapy and levothyroxine therapy.

Endocrine Abstracts

P485