Identifying risk factors of recurrence for clinically node negative papillary thyroid carcinoma with pathologic N1a

Whether or not to perform prophylactic central lymph node dissection (CLND) in the case of clinically node-negative papillary thyroid cancer (PTC) is controversial. The purpose of this study was to investigate the risk factors for recurrence in clinically node-negative PTC patients who underwent total thyroidectomy plus bilateral central neck dissection and was verified pathologic N1a.

We retrospectively reviewed the medical records of 1082 PTC patients who underwent total thyroidectomy and prophylactic bilateral CLND between January 2004 and December 2012. We used Cox-proportional hazard regression analyses in order to explore potential predictive factors for recurrence.

During a median follow-up (range) of 78 (12-158) months, recurrence occurred in 62 (5.7%) patients. Main tumor size more than 1 cm, gross extrathyroidal extension (ETE), positive lymph node (LN) more than 3, and LN ratio > 0.5 were all significantly associated with recurrence according to univariate analysis. In model I multivariate analysis (tumor size, gross ETE, LN ratio), LN ratio > 5 (hazards ratio [HR], 4.794; 95% confidence interval [CI], 2.674-8.595; p < 0.001) was found to be predictive of recurrence. Gross ETE (HR, 1.794; 95% CI, 1.024-3.143; p = 0.041) and positive LN more than 3 (HR, 2.505; 95% CI, 1.513-4.146; p < 0.001) were predictors for recurrence in model II multivariate analysis (tumor size, gross ETE, the number of positive LN).

We recommend that surgeons try to focus completely on performing prophylactic CLND for patients with suspicious gross ETE during preoperative evaluation. Close monitoring and thorough management are needed for clinically node-negative PTC patients with LN ratio of more than 0.5 and more than 3 positive LN in the central compartment.