Factors associated with distant metastasis in pediatric thyroid cancer: evaluation of the SEER database

OBJECTIVES: Controversies regarding factors associated with distant metastasis in pediatric thyroid cancer remain among the scientific community. The aim of this study was to investigate factors influencing distant metastasis in pediatric thyroid cancer. METHODS: We reviewed 1376 patients (aged 2 to 18 years) with thyroid cancer treated between 2003 and 2014. Data collected and analyzed included sex, race, age at diagnosis, year of diagnosis, pathological type, number of tumor foci, tumor extension, T-stage, N-stage, surgical procedure and radiation. Univariate and multivariate analyses were conducted to evaluate factors influencing distant metastasis of pediatric thyroid cancer. RESULTS: In the univariate analysis, factors influencing distant metastasis of thyroid cancer were age at diagnosis (P < 0.001), N-stage (P < 0.001), number of tumor foci (P = 0.003), tumor extension (P < 0.001) and T-stage (T1 vs T2 (P = 0.803), T3 (P < 0.001) and T4 (P < 0.001)). In multivariate analysis, factors influencing distant metastasis of thyroid cancer were age at diagnosis (P = 0.001), N-stage (P < 0.001) and T-stage (T1 vs T3 (P = 0.036) and T4 (P < 0.001)). Sex, race, year of diagnosis, pathological type, number of tumor foci, tumor extension, surgical procedure and radiation had no significant influence on distant metastasis (all P > 0.05). Furthermore, according to chi-squared test, younger pediatric thyroid cancer patients with higher T- and N-stages are more likely to have distant metastasis. CONCLUSION: Age at diagnosis, T-stage and N-stage influence distant metastasis of thyroid cancer patients aged 2 to 18 years; accordingly, more radical treatments may need to be used for patients with those risk elements.