The new T3b category has clinical significance? SEER-based study

Area of Science:

• Oncology
• Surgical Pathology
• Cancer Staging

Background:

• The 8th edition AJCC staging system for differentiated thyroid carcinoma (DTC) removed minimal extrathyroidal extension (mETE).
• A new T3b category was introduced for gross ETE (gETE) invading only strap muscles.

Purpose of the Study:

• To investigate the prognostic value of the new T3b category in DTC.
• To assess the impact of the T3b classification on patient survival outcomes.

Main Methods:

• Retrospective analysis of 63,315 patients from the SEER database (2004-2012).
• Kaplan-Meier analysis, log-rank tests, and Cox regression models were used.
• Propensity-score matching (PSM) was employed to minimize selection bias.

Main Results:

• Significant differences in cancer-specific survival (CSS) were observed across no ETE, mETE, T3b, and T4 categories.
• Both mETE and the T3b category were independently associated with poorer CSS compared to no ETE.
• PSM confirmed T3b is linked to worse CSS than no ETE and mETE.

Conclusions:

• Gross ETE (gETE) and minimal ETE (mETE) are independent prognostic factors in DTC.
• The new T3b category holds prognostic value and warrants consideration for medical professionals.
• Findings support potential future modifications to the TNM staging system for thyroid cancer.