Predictive factors for recurrence of differentiated thyroid cancer in patients under 21 years of age and a meta-analysis of the current literature.

The influence of predictors for recurrence in relation to recurrence-free survival was analyzed retrospectively in differentiated thyroid cancer (DTC) patients under 21 years of age who underwent primary surgical treatment and who had a pathological diagnosis of DTC between 1983 and 2012 at Fudan University Cancer Hospital. Recurrences were retrospectively analyzed using a Cox regression model for the hazard ratio (HR) according to the clinicopathological features. A meta-analysis was performed with respect to the potential predictors for recurrence from current related studies. In the present study, there were 146 young patients aged from 7 to 20 years, with a female/male ratio of 2.65/1. Female gender was the only factor significantly associated with recurrence according to univariate (HR = 2.812, P = 0.037) and multivariate (HR = 4.107, P = 0.024) Cox regression analyses. Meta-analyses revealed that multifocality (HR = 1.91, P < 0.05) and presentation at diagnosis (HR = 1.39, P < 0.05) were highly associated with recurrence in young DTC patients. However, female gender and other factors, such as age (≤10 vs. 11-20 years), PTC (PTC vs. FTC), extrathyroidal extension, lymph node metastasis, total thyroidectomy (total vs. less than total), radioiodine therapy, and radiation history, were not associated with recurrence in young DTC patients. In conclusion, multifocality and presentation at diagnosis are strong predictive factors of recurrence in relation to recurrence-free survival. We recommend studies with larger sample sizes and longer follow-up to verify the influence of predictors for disease recurrence in young patients.