Endocrine Abstracts

Introduction: Regional lymph node (LN) metastases have prognostic significance in differentiated thyroid cancer (DTC). Several studies demonstrated that lateral neck LN metastasis, classified as N1b, have a greater impact on overall survival than central LN metastasis. Our study aimed to assess the risk of N1a vs N1b involvement on outcome in patients with differentiated thyroid cancer (DTC), according to the 7th edition of the TNM staging system.

Methods/design: This was a retrospective study of 276 patients identified from our institutional database, who underwent surgery for DTC between 2000 and 2013. All patients had: lymph node metastasis, apparent complete tumour resection, without distant metastasis at diagnosis and nonaggressive histologic variant. The association between variables was assessed using chi-square and Student’s t-tests.

Results: All patients were followed for a minimum of 3 years postoperatively (146.3±87.1 months). Most patients had papillary thyroid cancer (99%). One hundred and twenty seven patients (46%) were classified as N1b and mean age was similar in both groups (46.6 years in N1b patients vs 47.5 in N1a; P=0.560). There was no significant association between N1b classification and extra-thyroid extension (44.9% of N1b patients vs 46.3% of N1a patients; P=0.812), tumour size (mean size was 23.3 vs 23.2 mm; P=0.958), persistence of disease (29.4% vs 21.1%; P=0.163), recurrence of disease (14.5% vs 9.1%; P=0.182) and disease specific-mortality (5% vs 1.5%; P=0.1).

Conclusion: Our results suggest that there is no difference in patients’ outcome with LN metastasis in the central neck compared to LN metastasis in the lateral neck or mediastinum, namely disease specific mortality, recurrence and persistence of disease. These data support the recently updated TNM classification in which lymph node metastases location is not considered for staging purposes.