Risk Factors Associated With Persistent Disease, Recurrence and Evidence of Disease 5 Years After Treatment in Papillary Thyroid Cancers Smaller Than 2 cm With and Without Gross Extrathyroidal Extension

Abstract

Purpose: Papillary thyroid carcinomas (PTCs) are often characterized by recurrence, persistent disease, and evidence of disease 5 years after treatment. Such factors may be influenced by gross extrathyroidal extension (ETE), which may not be easily distinguished preoperatively using ultrasonography. This study aimed to analyze whether the risk factors associated with the adverse events mentioned above would differ between PTCs measuring ≤2 cm within the thyroid gland and PTCs measuring ≤2 cm regardless of invasion status. Methods: We retrospectively analyzed all patients with PTC ≤2 cm who underwent surgery between 2002 and 2017. Patients were categorized into 2 groups: All (PTC ≤2 cm tumors including ETE) and No ETE (tumor ≤2 cm, limited to the thyroid gland). Results: In the All group, those with T4a and N1a/N1b status demonstrated a higher risk of recurrence, whereas the No ETE group tended to have more cases of disease recurrence at a younger age, margin-positive cases, and N1a/N1b patients. Furthermore, the All group demonstrated a higher rate of persistent disease in N1a/N1b patients, and evidence of disease 5 years after treatment was present in patients with positive ETE (N1b). Conclusion: Assessing tumor invasion preoperatively may be difficult; therefore, differences in factors associated with recurrence, persistent disease, and evidence of disease 5 years after treatment should be considered preoperatively.