Outcomes of the Tall-Cell Variant of Papillary Thyroid Carcinoma in Patients with Different Ages: A 17-Year Mono-Institutional Experience

Abstract

The tall-cell variant of papillary thyroid carcinoma (TCPTC) is the most common aggressive variant of papillary thyroid carcinoma (PTC) and typically occurs in older patients. In this study, we analyzed retrospectively the largest mono-institutional series of PTCs with tall-cell features (989 patients) over a 17-year period, re-evaluating tumors based on age at presentation and outcomes in different age groups. We divided patients into three age groups following different criteria (the criterion from the American Joint Committee on Cancer Tumor Node Metastasis (AJCC TNM) guidelines, criterion for the statistical division into tertiles and adolescent/post-adolescent criterion) to analyze the clinicopathological characteristics in different age groups, especially in terms of recurrence-free survival (RFS) and distant recurrence-free survival (DRFS). We obtained three main results: 1. the population is distributed among the different age groups, and therefore, this type of cancer is not exclusively found among those of an older age; 2. in the RFS analysis, we can see a higher probability of local recurrence in the younger and older groups and, unexpectedly, a lower probability of local recurrence in the "median age" group; and 3. in the DRFS analysis, we can observe a higher probability of distant recurrence in older patients. From a molecular perspective, no significant differences in the mutational status of BRAF were detected according to different age groups, while mutations in the TERT promoter were exclusively present in older patients of all age groups, highlighting the potential prognostic implications of TERT promoter mutations in PTCs. In conclusion, the results of this series confirm that TC morphology alone in PTCs does not have the same negative prognostic significance in the younger population as in the older population. The reason for these different outcomes remains unclear and needs further studies.

Keywords: age; clinical outcome; papillary carcinoma; tall cell; thyroid carcinoma.

Figure 1

Kaplan–Meier curves according to age groups (AgeAJCC criterion: patients < 55 years old and ≥55 years old; AgeNORM criterion, following statistical division into tertiles: patients ≤ 38 years old, 39–57 years old and ≥58 years old; AgeCOD criterion, following adolescent/post-adolescent classification: patients ≤ 25 years old and >25 years old). (A–C) Recurrence-free survival; (D–F) distant recurrence-free survival. (A–D) Stratification by AJCC age cut-off; (B–E) stratification by tertiles; (C–F) stratification by adolescent/post-adolescent classification.