Background and objective: Papillary thyroid microcarcinoma (PTMC) is recognized as a separate entity by the World Health Organization. Biological behaviour and clinical outcomes of PTMC are heterogenous. Presence of lymph node metastases (LNM) in this group of patients increases the risk of recurrence and makes optimal management in PTMC controversial (observation, lobectomy with or without preventive central ipsilateral dissection). The aim of this study was to describe risk factors for lymph nodal involvement in patients with PTMC.
Patients and methods: The Cadit-CAM study was designed to retrospectively analyze the clinical characteristics, treatments and outcomes of patients diagnosed of differentiated thyroid cancer (DTC) in Castilla La Mancha (CAM), a region in the central part of Spain. The cohort in Cadit-CAM study included 1434 patients from seven hospitals enrolled from 2001 to 2015. Patients with tumours ≤1 cm were selected. All underwent total thyroidectomy or lobectomy. Clinicopathological characteristics of patients with PTMC were reviewed. Univariate (χ2 and Students t test) and multivariate logistic regression analysis were used to identify predictors of LNM.
Results: 426 PTMC were included, women 78.9% with mean age at diagnosis 50.6±13.5 years. LNM were present in 12.7%. After surgery 54.2% received radioiodine. In univariate analysis male gender, age at diagnosis <45 years, multifocality, tumour size >5 mm and extrathyroidal extension were associated with LNM. The presence of thyroid autoimmunity was not associated with LNM. In multivariate analysis factors independently associated with LNM in PTMC were: male (OR 2.1 IC 95% 1.14.6 P<0.05), age at diagnosis <45 years (OR 2.6 IC 95% 1.44.9 P<0.01), multifocality (OR 2.8 IC 95% 1.55.4 P<0.01) and extrathyroidal extension (OR 6.0 IC 95% 2.615.5 P<0.001). 4 patients died from DTC. At final follow up 83.8% had excellent response, 13.8% indeterminate response, 0.9% biochemical incomplete response and 1.9% structural incomplete response.
Conclusions: PTMC in male younger patients (<45 years), with multifocal tumours and extrathyroidal extension are at risk of LNM. Treatment options in PTMC should be adapted to initial patient and tumour characteristics rather than tumour size.
18 - 21 May 2019
European Society of Endocrinology