Prognostic value of lymph node metastases of differentiated thyroid cancer (DTC) according to the local advancement and range of surgical excision

The analysis of prognostic significance of LN metastases, in DTC patients to verify the potential role of central neck lymphadenectomy on disease staging.

The group of 195 DTC patients, primarily operated between 2004 and 2005, was retrospectively analyzed. 184 patients after radical operation, with no distant metastases diagnosed before surgery, were included into analysis. LN metastases were observed in 55 of cases (28%). In 124 cases only dissection of central LN compartment was performed, in 36 patients also uni- or bilateral modified cervical lymphadectomy was carried out. In 24 patients with tumor limited to the thyroid gland without suspicious lymph nodes, the routine central lymph node dissection was not done.

Median follow-up was 4 years. The 5-year overall and disease free survival standardized ratio were 100% and 95% respectively. The risk of LN metastases increased with the more locally advanced cancer. In the group of 124 patients, in whom only central LN dissection was performed, LN metastases were diagnosed in 15 cases (12%). No significant relation between multifocality and frequency of central and/or lateral LN metastases was noticed. Significant correlation between N feature and extrathyroidal invasion was observed (p = 0,0003). The presence of LN metastases was related to worsening of disease free survival from 99 to 90%. During the follow-up recurrence occurred in 6 (3%) cases. In 24 patients in whom only total thyroidectomy was done, no local or distant recurrence was observed. The assessment of early postoperative complications (hypoparathyroidism, paresis of vocal cords) indicated that the frequency of early calcium balance disturbances was significantly lower in patients in whom central LN dissection was not performed (p = 0,04)

Our result indicate that in the early diagnosis of thyroid cancer, the occurrence of LN DTC metastases is rarer and was observed only in 12% of elective dissections of central LN node compartment, if no lateral dissection was indicated due to the lack of clinical suspicion. In DTC patients with tumor diameter <1 cm and no sonographical or inraoperative suspicion on LN involvement, routine central lymphadenectomy may be not obligatory.