The frequency of risk pathological characteristics in clinically low-risk papillary thyroid microcarcinoma suitable for active surveillance.

Abstract

Active surveillance has emerged as an initial management strategy for patients with low-risk papillary thyroid microcarcinoma (PTMC). The main objective of this research was to investigate the frequency of risk pathological characteristics among patients with clinically low-risk PTMC who are suitable for Active Surveillance. A retrospective review was conducted on patients who underwent lobectomy for PTMC between January 2013 and December 2018. Patients with bilateral tumors, macroscopic multifocal tumors, macroscopic extrathyroidal extension (ETE), clinical lymph node metastases, macroscopic extranodal extension (ENE), distant metastases, a history of neck radiation or familial thyroid cancer were excluded. Pathological characteristics were collected from the postoperative pathological results. Aggressive variants, multifocality, ETE, lymphovascular invasion (LVI), perineural invasion (PNI), metastatic lymph nodes (LNs) ≥ 5, and ENE were defined as risk characteristics. The study included 4923 patients, of whom 1229 (25.0%) were male. The mean age was 43years. A total of 2250 patients (45.7%) exhibited risk characteristics. Among them, 15 patients presented with aggressive variants, and 1813 patients (36.8%) had ETE. Multifocality, LVI, and PNI were observed in 551 (11.2%), 21 (0.4%), and 40 (0.8%) patients, respectively. A total of 139 patients (2.8%) had five or more metastatic LNs, and ENE was identified in 140 patients. Notably, 172 patients (3.5%) fulfilled the criteria for completion thyroidectomy, as they had aggressive variants, LVI, or five or more metastatic LNs. Nearly half of the patients diagnosed with clinically low-risk PTMC exhibited risk pathological characteristics, and a small proportion of patients met the criteria for completion thyroidectomy.