Comparison of the clinicopathologic features and prognosis of bilateral versus unilateral multifocal papillary thyroid cancer: An updated study with more than 2000 consecutive patients

Abstract

BACKGROUND Bilaterality is common in papillary thyroid cancer (PTC), but its clinical and prognostic implications are still controversial, and it remains unclear whether its behavior is more aggressive than multifocality. METHODS The clinicopathologic features of 2211 consecutive patients with PTC who underwent surgical treatment at the authors' institute between 1997 and 2011 were reviewed. Among these surgical patients, 425 (19.2%) had bilateral PTCs, and 1786 had unilateral PTCs. The patients who had unilateral PTCs were subdivided into a group with unilateral-multifocal PTCs (210 patients) and a group with solitary PTCs (1576 patients). The 10-year disease-free survival (DFS) rates were calculated to compare the prognosis between groups. B-Raf proto-oncogene, serine/threonine kinase (BRAF) mutation status was examined by direct DNA sequencing. RESULTS Patients who had bilateral PTCs were likely to have larger tumors, higher rates of extrathyroid extension and lymph node metastasis, and more advanced tumor stage than those who had unilateral-multifocal PTCs. Multivariate analysis identified only lymph node metastasis as an independent risk factor for PTC recurrence (P