[Evaluation of central lymph node dissection for papillary thyroid carcinoma in cN0 T1/T2]

Objective: To evaluate the application of the central lymph node dissection (CLND) for papillary thyroid carcinoma (PTC) in cN0 T1/T2. Methods: Retrospective analysis of 532 cases with PTC in cN0 T1/T2 who underwent CLND between October 2014 and September 2016 in the Department of Thyroid Surgery, the First Affiliated Hospital of the Kunming Medical University. The incidence of central lymph node (CLN) metastasis and risk factors were analyzed. Results: CLN metastasis rates: 41.2% (42/102) in males vs 34.9% (150/430) in females, P=0.252; 33.9% (116/342) in single focal carcinoma vs 40.4% (74/183) in multifocal carcinoma, P=0.157; 44.0% (125/284) in patients with 45 years old or less vs 27.0% (67/248) in patients more than 45 years old, P=0.000; 30.3% (113/373) in microcarcinoma vs 50.9% (81/159) in non-microcarcinoma, P=0.000.In unilateral lesions, ipsilateral CLN metastasis was correlated with the tumor diameter (P=0.012), but not with the number of lesions (P=0.653). also contralateral CLN metastasis was correlated with the tumor diameter (P=0.000), but not with the number of lesions (P=0.815). For the left or right unilateral single focal lesion, the tumor diameter was not correlated with the metastasis of the posterior to right recurrent laryngeal nerve central lymph nodes (LN-prRLN-CLN) (P=0.652, P=0.088). But in bilateral multifocal carcinoma the tumor diameter was correlated with metastasis of LN-prRLN-CLN (P=0.039). Conclusions: Prophylactic CLND is reasonable for PTC in cN0 T1/T2. A bilateral CLND should be conducted for patients with bilateral multi-focus cancer and unilateral or bilateral non-microcarcinoma, especially in patients more than 45 years old. For unilateral single focal microcarcinoma on the right, the content of CLND should be from laryngeal nerve on right center to posterior branche; for unilateral single focal microcarcinoma on the left side, the left CLND should be conducted. An ipsilateral CLND can be considered in patients with unilateral multifocal microcarcinoma, and generally a routine dissection of the LN-prRLN-CLN is not required, however for bilateral non-microcarcinoma and the the non-microcarcinoma on the right side, the LN-prRLN-CLN dissection should be conducted.