Scoring system for predicting recurrences in patients with papillary thyroid microcarcinoma

ContextPapillary thyroid microcarcinomas (PMC) defined as tumors ≤10 mm in diameter (including pT1a and pT3 according to the latest pTNM classification) have good prognosis, although recurrence is possible. Clinicians are interested in using a scoring system for predicting recurrences.ObjectiveTo identify the prognostic factors for recurrence in patients with PMC and to develop a scoring system based on lymph node involvement, multifocality, and sex. To determine the impact of extrathyroidal invasion (ETI) and a threshold value for analyzing multifocality.MethodsSingle-center retrospective study of a cohort of 1669 patients with PMC managed from 1960 to 2007. The Kaplan–Meier survival rate and prognostic factors of events were analyzed using log-rank tests and uni- and multivariate Cox model-based analyses. A scoring system was proposed.ResultsSixty-eight recurrences were observed. Initial lymph node metastases (P=0.0001), multifocality (P=0.05), and male sex (P=0.01) were significantly associated with recurrence, although there was a period effect (after 1990). PMC size was not a significant variable. Our scoring system allows us to separate patients into three risk groups according to their recurrence-free probability. For PMC Nx patients, total foci size of multifocal tumors >20 mm was significantly associated with recurrence (P