Routine Level 2b Dissection may be Recommended Only in N1b Papillary Thyroid Carcinoma with Three- or Four-Level Lateral Lymph Node Metastasis.

BACKGROUND

Due to the low incidence of level 2b metastasis and the risk of spinal accessory nerve injury, previous studies have argued against routine level 2b dissection for N1b papillary thyroid carcinoma (PTC). However, other studies have suggested the importance of including level 2b during lateral neck dissection. Therefore, this study aimed to determine the necessity of routine level 2b dissection.

METHODS

The study retrospectively reviewed 327 N1b PTC patients who underwent unilateral modified radical neck dissection between January 1997 and May 2016.

RESULTS

The incidence of level 2b metastasis was 10.4 %, compared with 53.5 % for level 2a metastasis. The univariate analysis showed that large tumor size (p = 0.027) and simultaneous lateral lymph node metastasis (LLNM) (p = 0.002) were significantly associated with level 2b metastasis. The multivariate analysis showed that three-level (adjusted odds ratio [OR] 6.032; p = 0.020) and four-level (adjusted OR 9.398; p = 0.012) simultaneous LLNM were independent predictors for level 2b metastasis.

CONCLUSIONS

Due to the low incidence of level 2b metastasis, routine level 2b dissection may not be necessary for N1b PTC patients. Level 2b dissection may be reserved for patients with more than three-level simultaneous LLNM or clinical/radiological evidence of level 2b metastasis.