Influence of ultrasound-guided fine needle aspiration biopsy on cervical lymph node metastasis and prognosis of papillary thyroid microcarcinoma

Abstract Purpose To analyze the potential association between UGFNA and cervical lymph node metastasis (CLNM) of papillary thyroid microcarcinoma (PTMC) and whether it would influence the long-term prognosis of PTMC. Then we could give advice for the application of UGFNA for thyroid nodules less than 1cm. Methods A total of 367 adult patients with PTMC who underwent thyroidectomy in our hospital during January 2014 and December 2015 were enrolled in this retrospective cohort study. Univariate and multivariate analysis were conducted to explore the potential risk factors of CLNM. Propensity score (PS) matching was performed to select patients with homogeneous baseline characteristics. Then the rate of CLNM was compared in matched samples by chi-squared (χ2). Survival analysis was made by Kaplan-Meier method in PS-matching cohort. Results CLNM rate in PS-matching cohort showed no significant difference between UGFNA group and non-UGFNA group. (29.5% vs 23.7%, P>0.05). Multivariate analysis showed that male sex (OR=3.997, 95%CI 2.148~7.439, P<0.01), larger tumor size (OR=2.319, 95%CI 1.285~4.186, P<0.01) were independent risk factors of CLNM. With a median follow-up of 63.8 months (range 3.1-84.9 months), the 5-year cumulative recurrence-free survival (RFS) rate was 99.3% in UGFNA group and 97.7% in non-UGFNA group. After PS-matching, Kaplan-Meier curves showed no significant difference from each other (P >0.05). Conclusions UGFNA was a very safe diagnostic tool, which would not influence the CLNM rate and long-term prognosis of patients with PTMC. Regardless of the costs, we recommend routine UGFNA for suspicious thyroid nodules ≦1cm.