Purpose: In the most recent version of the UICC TNM classification system for thyroid carcinoma, tumors with minimal extrathyroid extension were classified as T3. In this study, we investigated whether this upgrading is appropriate for papillary thyroid carcinoma.
Methods: We investigated the difference in the relapse-free survival (RFS) rate between patients with tumors having no, minimal, and massive extrathyroid extension in a series of 502 patients over the age of 45 years.
Results: Patients with tumors showing massive extension showed a worse RFS rate except for those with tumors measuring 1 cm or less. However, there was no significant difference in RFS between tumors measuring 4 cm or less showing no or minimal extension. In an investigation of 409 patients without any clinically apparent node metastasis, the RFS of patients with tumors larger than 4 cm with massive extension was significantly worse than those with tumors measuring 4 cm or less, while the RFS of patients with tumors with either no or minimal extension did not depend on the tumor size.
Conclusions: These findings suggest that tumors with minimal extension should be classified to have the same T grade as those without such extension, and upstaging of such tumors is therefore not appropriate.