Active Surveillance for T1bN0M0 Papillary Thyroid Carcinoma

Area of Science:

• Endocrinology
• Oncology
• Surgical Oncology

Background:

• Active surveillance has demonstrated low progression rates (5-10%) for T1aN0M0 papillary thyroid microcarcinoma (PTC).
• The 2015 American Thyroid Association guidelines support active surveillance for very low-risk PTC.
• Long-term data on active surveillance for T1b PTC tumors are lacking.

Purpose of the Study:

• To evaluate the long-term outcomes of active surveillance for T1bN0M0 PTC.
• To compare the progression rates of T1bN0M0 PTC under active surveillance with those of T1aN0M0 PTC.
• To analyze the outcomes of T1bN0M0 PTC managed with immediate surgery.

Main Methods:

• A prospective trial included 360 T1aN0M0 PTC patients and 61 T1bN0M0 PTC patients who opted for active surveillance.
• 331 T1bN0M0 PTC patients underwent immediate surgery for comparison.
• Outcomes including tumor size increase and lymph node metastasis were monitored over a mean follow-up of 7.4 years.

Main Results:

• After a mean of 7.4 years, 7% of T1bN0M0 tumors and 8% of T1aN0M0 tumors showed size increase, with no significant difference between groups.
• Lymph node metastasis developed in 3% of T1bN0M0 patients and 0.8% of T1aN0M0 patients (p=0.10).
• For T1bN0M0 tumors, weak calcification and rich vascularity predicted size increase, while younger age predicted lymph node metastasis. No recurrence was observed in T1bN0M0 tumors <15mm treated with surgery.

Conclusions:

• Active surveillance is a suitable management option for carefully selected T1bN0M0 PTC patients.
• Progression rates for T1bN0M0 PTC under active surveillance are comparable to those of T1aN0M0 PTC.
• Risk factors for progression in T1bN0M0 PTC include tumor calcification, vascularity, and patient age.