CLINICAL FEATURES IN DIFFERENTIATED THYROID CARCINOMA STRATIFIED BY LYMPH NODE STATUS

OBJECTIVE: Cervical lymph node (CLN) metastases (mets) often occur in differentiated thyroid cancer (DTC), especially in the central compartment, and are a major predictor of local recurrence. We examined clinical endpoints in three groups of patients based on status of lymph node involvement: those with definite lymph node involvement (N1), negative lymph nodes (N0), and no lymph nodes resected (Nx). We correlated these endpoints with clinical and pathologic features of these patients.

METHODS: Medical records of 261 patients with DTC who underwent thyroidectomy between 2006 and 2018 at our center were reviewed. Lymph node status of patients was categorized based on American Joint Committee on Cancer (AJCC) 8th edition criteria as N1, N0, and Nx. We performed statistical analysis to assess the differences among these groups, using one-way analysis of variance. When significant differences were found, pairwise comparisons were conducted among the three groups. Statistical significance was defined as 2-tailed P<.05 for all tests.

RESULTS: There were significant differences among the groups in tumor multicentricity, tumor category/size, AJCC stage, and the presence of thyroglobulin auto-antibodies (TgAbs). There were no difference in age, gender, or histopathology. N1 patients had a higher incidence of multicentricity, larger tumor sizes, and were more likely to have elevated TgAbs. There were no significant differences between the N0 and Nx groups.

CONCLUSION: This study shows that larger and multi-centric tumors are associated with increased likelihood of CLN mets in DTC. We suggest increased vigilance for CLN mets in tumors >2 cm, multicentric tumors, and patients with elevated TgAbs.

ABBREVIATIONS: AJCC = American Joint Committee on Cancer; CLN = cervical lymph node; DTC = differentiated thyroid cancer; FTC = follicular thyroid cancer; mets = metastases; N0 = no cancer in any lymph nodes; N1 = cancer in a lymph node; N1a = cancer in a central compartment lymph node; N1b = cancer in a lateral neck lymph node; Nx = lymph nodes not resected or examined; PTC = papillary thyroid cancer; TgAb = thyroglobulin auto-antibody.