[Related factors of central lymph node metastasis in papillary thyroid carcinoma]

To study the related factors of central lymph node (CLN) metastasis in papillary thyroid carcinoma (PTC),the indications and the extent of central neck dissection (CND).

A total of 153 cases treated between Jan. 2009 and Dec. 2010 was analysed retrospectively. Of the cases 28 males and 125 cases females, with a mean age of (44 ± 14) years. T1, T2, and T3 diseases accounted for 51, 10 and 81 cases, respectively; I, II, III and IV diseases for 88, 3, 26 and 36 cases, respectively. Multifocal tumors were found in 63 cases. The related clinicopathologic factors were analyzed, including sex, age, tumor size, extrathyroidal extension, and multifocal tumor.

All the cases had total/near total thyroidectomy and CND, of them 64 cases had unilateral neck dissection and 18 cases had bilateral neck dissection. CLN metastases existed in 68.6% (105/153) cases, 37.2% (57/153) for unilateral and 31.4% (48/153) for bilateral respectively. The rates of CLN metastasis were 86.6% (71/82) in cN1 cases and 47.9% (34/71) cN0 cases, respectively,and the rates of bilateral CLN metastases were 45.1% (37/82) in cN1 cases and 15.5% (11/71) in cN0 cases. Multivariate analysis showed that extrathyroidal extension (P = 0.002, OR = 3.502) was an independent risk factor for CLN metastasis and that lateral neck lymph node metastasis (P = 0.028, OR = 3.080), surrounding tissue invasion (P = 0.014, OR = 3.113), and maximum tumor diameter greater than 1 cm (P = 0.012, OR = 3.732) were independent risk factors for bilateral CLN metastases.

It is indicated that ipsilateral CND should be obligatory for PTC. Intraoperative frozen section examination should be routine. Bilateral CND should be conducted when ipsilateral CLN metastases accompanied by one of following issues such as more invasive tumor (surrounding tissue invasion, T3 or T4 disease), maximum tumor diameter greater than 1 cm, and lateral neck lymph node metastasis.