Predictive factors of level IIb lymph node metastasis in patients with papillary thyroid carcinoma

The extent of neck dissection (ND) appropriate for necks yielding clinical evidence of metastases of papillary thyroid carcinoma (PTC) is controversial. The need for level IIb lymph node (LN) dissection is particularly uncertain in view of its association with postoperative shoulder dysfunction. In the present study, we examined the frequency, pattern, and predictive factors of level IIb LN metastases in PTC patients with clinically positive lateral neck nodes.

We reviewed the medical records of 76 PTC patients who underwent therapeutic lateral ND for the treatment of clinically positive lateral neck nodes between March 2005 and July 2008. ND specimens were separately obtained for analyzing LN involvement with respect to neck level.

Metastatic disease at levels II, III, IV, and V, was seen in 40 (52.6%), 55 (72.4%), 52 (68.4%), and 12 (15.8%) of the patients, respectively. The metastasis rate in level IIb was 11.8% (9 of 76). By univariate analysis, the rate of level IIb LN metastasis was significantly higher in patients with positive level IIa LNs and positive LNs in all lateral neck levels (levels IIa + III + IV) (P < .05). Multivariate analysis showed that positive LN involvement in all lateral neck levels (IIa + III + IV) was an independent predictive factor of level IIb LN metastasis (P = .044, odds ratio = 9.692).

Level IIb LN dissection may be omitted in the treatment of positive neck nodes in PTC patients if multilevel involvement including level IIa involvement is absent.