Papillary thyroid microcarcinoma: distinct form or cancer growth stage?

Abstract

Background. Over the past decades an increase in the incidence of papillary thyroid microcarcinoma (PTMC) has been observed throughout the world owing to the improved diagnostics. There are many different opinions about the aggressiveness degree of this group of tumors, as well as about the tactics of managing patients with PTMC.Aim of the study is the identification of the prognostic factors responsible for the features of the clinical course, including the more aggressive one.Materials and methods. A study was carried out with a detailed analysis of a group of patients with papillary thyroid cancer ≤1 cm in size and the existing clinical data of regional and distant metastases. All patients underwent thyroidectomy with bilateral central cervical lymph node dissection. Factors such as gender, patient age, bilaterality, extrathyroid extension, the presence or absence of a capsule around the tumor node, the absence or presence of metastases in the central part were assessed. In 26.6% histological examination revealed metastatic lesions of the central group lymph nodes. Latent metastases were detected in 24.2% of women and 43% of men, in 36.7% of patients <55 and in 14.3% of patients ≥ 55 years, in 29.5% with the absence of the node capsule and in 19.3% with encapsulated tumors, in 48.1% with multicentric growth and in 19.5% with a solitary neoplasm, in 21.7% with a tumor size ≤0.5 cm and in 27.9% with a node of 0.6–1 cm, in 24% with the absence of invasion of the thyroid capsule and in 31% with the presence of extrathyroid invasion, in 21% of patients with typical, in 26% with follicular and 43% with mixed papillary cancer. 95 patients received radioiodine therapy. No additional metastases were found in them.Results. When conducting univariate analysis, the main signs influencing the development of metastases in the central zone were age up to 55 years (p = 0.009, χ2 = 6.919) and multicentric neoplasm (p = 0.004, χ2 = 8.530); in multivariate analysis, similarly, age younger 55 years (p = 0.000, Exp B = 0.011, CI 95.0% 0.001–0.106) and multifocality (p = 0.027, Exp B = 2.686, CI 95.0% 1.119–6.448).Conclusion. PTMC is not a separate group or tumor morphotype, and the determination of treatment tactics for this group of patients should be based not only on the size of the tumor, but on the clinical and biological parameters of the tumor.