ABSTRACT
PURPOSE: The purpose of the present study was to identify more useful parameters for predicting behaviors of multifocal papillary thyroid carcinoma (PTC). MATERIALS AND METHODS: We investigated dominant tumor diameter (TD), total tumor diameter (TTD), and total surface area (TSA) in tumors from 588 patients and evaluated their usefulness as parameters for assessment of tumor behaviors in multifocal PTCs. RESULTS: In 588 PTCs, tumor multifocality was found in 179 PTCs (30.4%). Multifocal tumors were significantly associated with extrathyroidal extension, lymph node metastasis, and higher tumor stage grouping (p3.14 cm2 had higher rates of nodal metastasis than mPMCs with TSA 1.0 cm and with TTD 3.14 cm2 than in unifocal papillary thyroid microcarcinomas (uPMCs) (TD 1.0 cm) (p=0.244). CONCLUSION: Our results suggest that mPMCs with TSA >3.14 cm2 show more aggressive behavior than uPMCs and mPMCs with TSA < or =3.14 cm2. TSA could be useful in distinguishing aggressive mPMCs from favorable cases.