Purpose: Papillary thyroid carcinoma (PTC), the most common thyroid cancer histotype, has a good prognosis even when spread to the neck lymph node (LN). The prognostic role of LN metastases' location is still controversial. The aim of the present study was to evaluate the clinical relevance of the number and location of LN metastases at presentation in PTCs.
Methods: This retrospective study included a consecutive series of 1653 PTC patients followed for a mean period of 5.9 years in a referral thyroid cancer clinic. All patients have undergone thyroidectomy with the dissection of at least six LNs. According to the LN status, patients were subdivided into 569 N0 (34.4%), 644 N1a (39.0%, central compartment) and 440 N1b (26.6%, latero-cervical compartment).
Results: Age at diagnosis was significantly lower in N1b (39.8, IQR 30.7-51.6) and N1a (40.1, IQR 31.3-50.1) than in N0 (44.7, IQR 36.6-55.0 yrs). The male gender was more prevalent in N1b than in N1a and N0 (F/M = 1.9/1, 4.0/1 and 5.5/1, respectively). Persistent/recurrent disease at last control was significantly more frequent in N1b (29.8%) than in N1a (14.3%), and in N1a than in N0 (4.2%) (p < 0.01 for all). Also, distant metastases were significantly (p < 0.001) more frequent in N1b (14.1%) than in N1a (4.3%) and N0 (1.6%). LN metastases' number (>5) was a significant risk factor for persistent/recurrent disease only for N1a patients.
Conclusions: These data indicate that persistent/recurrent disease and distant metastases are significantly more frequent in patients with latero-cervical LN (N1b) metastases and that the LN location should be used for a better postsurgical risk stratification.
Keywords: Latero-cervical lymph node metastases; Papillary thyroid cancer; Thyroid cancer; Thyroid cancer metastases; Thyroid cancer outcome.