PTMC is defined as a papillary thyroid cancer smaller than 10 mm in its greatest diameter. It is the most common form of differentiated thyroid cancer and its prognosis is known to be very favorable. The aim of this study is to identify its biologic behavior and to formulate a reasonable therapeutic strategy for the treatment of PTMC.

379 patients with papillary thyroid cancer were analyzed. Each patient was diagnosed preoperatively or postoperatively and treated between Jan. 2000 and Dec. 2007. Among these patients, 143 had been identified as having PTMC (37.7%) with a mean tumor size of 0.72 cm in diameter.

There were no significant differences of the clinical characteristics such as gender, age, the operative methods, or multicentricity between the PTMC group and the non-PTMC group, except for LN metastases. Also, there were fewer symptoms of palpable neck mass and preoperative findings such as capsular invasion and microcalcification in the PTMC group. We performed unilateral lobectomy with or without central compartment neck node dissection for the early stage diseases, but for the later stages of disease we performed near-total or total thyroidectomy with routine central compartment neck node dissection. And for the patients with lateral node enlargement, we performed ipsilateral modified radical neck dissection (MRND).

This study shows that PTMC is quite similar to conventional papillary thyroid cancer in its biological behavior, and we conclude that total thyroidectomy with central compartment neck node dissection is the proper therapeutic strategy to treat PTMC. However, further study is necessary for identifying the low-risk and high-risk patients with PTMC.