Effect of Hashimoto's thyroiditis on degree of necklymph node dissection and prognosis in patients with papillary thyroid carcinoma

  Objective  To investigate the effect of Hashimoto's thyroiditis (HT) on the degree of neck lymph node dissection and prognosis in patients with papillary thyroid carcinoma (PTC).

  Methods  The clinical and pathological materials of 180 PTC patients underwent total thyroidectomy combined with central lymph node dissection in Wuhan City Red Cross Hospital from January 2013 to December 2015 were retrospectively analyzed. According to the postoperative HT diagnosis, the patients were divided into PTC combined with HT group (n=55) and PTC without HT group (n=125), and all the patients were followed up for 5 years after operation. According to the initial response to treatment, dynamic risk stratification (DRS) was performed according to the guidelines of the American Thyroid Association in 2015. The clinicopathological characteristics and DRS of the two groups were compared. The value and the best cut-off point of the number of positive lymph nodes (PLN), the number of lymph nodes yield (LNY) and lymph nodes ratio (LNR) in predicting structural relapse or persistent disease were evaluated by receiver operating characteristic (ROC) curve, and the risk factors of structural relapse or persistent disease were further evaluated by Cox proportional hazards model.

  Results  There was no significant difference in central cervical lymph node metastasis between the two groups (P=0.508), which suggested that complicating with HT was unable to reduce the risk of cervical lymph node metastasis. LNY in the PTC combined with HT group was significantly more than that in the PTC without HT group (P=0.001). LNR was significantly lower in the PTC with HT group (P=0.040), and was independently associated with structural relapse or persistent disease (OR=59.574, P=0.012). After adjusting for other clinicopathological factors, HT itself was negatively correlated with structural relapse or persistent disease (OR=0.064, P=0.032).

  Conclusion  Regardless of the extent of lymph node dissection, HT is an independent prognostic factor for PTC patients.