Differentiated thyroid cancers 11-20 mm in diameter have clinical and histopathologic characteristics suggesting higher aggressiveness than those < or =10 mm.

Objective: To compare characteristics and outcomes of differentiated thyroid cancers < or =10 mm with those 11-20 mm in diameter.
Design: Retrospective chart review of 426 patients with thyroid carcinoma < or =20 mm diagnosed and treated between 1990 and 2004 in one university clinic.
Main Outcomes: Lymph node metastases were more frequent at diagnosis in 11-20 mm than in < or =10 mm cancers (p < 0.001). The prevalence of distant metastases did not differ between < or =10 mm and 11-20 mm cancers. One hundred and thirty-three patients (73%) with tumors 11-20 mm were disease free 2 years after 131I treatment, and no recurrence has been observed over 2-14 years of follow-up. Forty-one patients (22%) with cancers 11-20 mm (N1 or M1) required 2-4 years to become disease free. Neck lymph node recurrence was observed in nine patients (4.9%) 4 months to 14 years after surgery and (131)I therapy. Four patients (1.6%) with cancers < or =10 mm in diameter had cancer recurrence (p = 0.05 compared to the 11-20 mm cancers). Based on the presence of distant metastases at diagnosis and recurrence of disease during follow-up, cancers 11-20 mm in diameter seemed more aggressive than those < or =10 mm (p < 0.05).
Conclusion: Cancers 11-20 mm seem more aggressive than those < or =10 mm.