167P Predictive factors for central neck lymph node metastasis in patients with papillary thyroid microcarcinoma without suspicious metastasis by preoperative ultrasonography

Abstract

Background Papillarymicrocarcinoma(PTMC) isasmallpapillarythyroidcarcinoma measuring 1cm or less in diameter. Recently, incidence of PTMC has been increased due to an increase in the detection of subclinical disease such as small and low-risk carcinomas with ultrasonography and fine needle aspiration cytology. However, there is central neck lymph node metastasis in patients with PTMC without clinical evidence of metastasis by preoperative ultrasonography. We performed analysis to determine the influencing factors for central lymph node metastasis in PTMC although there was no clinical evidence of metastasis by preoperative ultrasonography. Methods We analyzed retrospectively 625 patients with PTMC underwent thyroid surgery at Chosun University Hospital from January 2002 to December 2012. Finally, we included 575 patients who had no evidence of lymph node metastasis by preoperative ultrasonography. We reviewed medical records including clinical information and pathologic report. Results Central lymph node metastasis was found in 81 patients (14.1%) among total 575 patients. A lymph node metastasis occurred frequently according to univariate analysisin patients withfollowingfactors;morethan0.5cminlargesttumorsizeby preoperativesonographyandpathologicreports(p=0.048andp=0.001,respectively) andlymphovascularinvasion(p<0.001).Multivariateanalysisrevealedthatthegender (Female vs Male), pathologic tumor size (0.5 ~ 1cm vs < 0.5cm) and lymphovascular invasion(YesvsNo)weresignificantassociatedfactorsforlymphnodemetastasis [Odds ratio (OR)=0.498, 95% confidence interval (CI)=0.250-0.992, P = 0.047; OR = 2.450, 95% CI = 1.313-4.570, P = 0.005; and OR = 24.954, 95% CI = 2.430- 256.217,P=0.007,respectively]. Conclusions Male gender, larger tumor size (>0.5cm) and lymphovascularinvasion were found as the risk factors for central neck lymph node metastasis in patients with PTMC without suspicious clinical evidence of node metastasis. We concluded that prophylactic central neck lymph node dissection might be required in these cases of PTMC. Legalentity responsiblefor thestudy: N/A Funding N/A Disclosure All authors have declared no conflicts of interest.