Survival of aggressive variants of papillary thyroid carcinoma in patients under 55 years old: a SEER population-based retrospective analysis.

Background: Patients younger than 55 years of age with papillary thyroid carcinoma (PTC) have excellent survival. Diffuse sclerosing variant (DSV) and tall cell variant (TCV) of PTC are associated with aggressiveness; the survival of patients <55 years of age with these variants is still unclear. We aim to investigate the clinicopathological features and survival of these variants in the age group <55 years.

Methods: All adult patients (<55 years old) with DSV, TCV and conventional PTC (CPTC) came from the Surveillance, Epidemiology, and End Results program (1988-2013). Kaplan-Meier method and log-rank test were used to analyze the survival. Prognostic factors associated with survival were analyzed by Cox multivariate regression.

Results: There were 280 DSV, 615 TCV, and 56287 CPTC in the age group <55 years. DSV and TCV were associated with multifocality, extrathyroidal extension, lymph node and distant metastasis (all p < 0.05). The 10-year disease-specific survival (DSS) of TCV was worse than CPTC (96.3 vs. 99.4%, p < 0.01), but there was no significant difference between DSV and CPTC (99.5 vs. 99.4%, p > 0.05). Cox multivariate regression showed TCV was the independent predictor of DSS (HR: 5.39, p < 0.01).

Conclusion: In the age group <55 years, DSV and TCV are more likely to exhibit aggressive characteristics than CPTC. Patient <55 years of age with DSV have excellent survival likewise, while patients <55 years of age with TCV carry worse survival. Further investigation for the recurrence risk of patients <55 years with these variants would contribute to optimal clinical management making.