Is 55 years an optimal age cutoff point for clinical staging in T1 papillary thyroid cancer?

This study aims to determine the optimal age cutoff for T1 papillary thyroid cancer (PTC), with a particular focus on the T1a and T1b subgroups.

A retrospective review of electronic medical records was conducted to identify patients who underwent thyroidectomy at our institution from January 2013 to December 2018.

The study cohort consisted of 2,862 patients, including 765 men (26.7 %) and 2,097 women (73.3 %). Survival analysis demonstrated significantly poorer recurrence-free survival (RFS) in patients aged ≥55 years (p < 0.001). Patients were stratified into T1 (tumor size ≤2 cm, n = 2,328) and non-T1 (tumor size >2 cm, n = 534) subgroups. Among the non-T1 subgroup, older patients exhibited significantly inferior RFS, consistent with the overall cohort (p < 0.001). However, this difference was not observed in the T1 subgroup (p = 0.079). Within the T1 PTC subgroup, significant differences were identified between T1a and T1b patients concerning gender distribution, tumor size, clinical lymph node-positive status (cN1), total thyroidectomy, bilaterality, presence of Hashimoto's thyroiditis, central lymph node metastasis, lateral lymph node metastasis, and radioiodine treatment (all p < 0.05). Further analysis indicated that when stratified by an age cutoff of 65 years, the prognosis for T1b patients was statistically significant (p = 0.018), whereas the prognosis for T1a patients was not statistically significant (p = 0.64).

The clinicopathologic characteristics of T1b patients differ significantly from those of T1a patients. Age may not be a critical factor in the prognostic staging system for T1a PTC patients, whereas 65 years appears to be a more appropriate age cutoff for T1b patients.