ABSTRACT
Objective To evaluate the clinical and pathological feature,as well as risk factors of lymph node metastasis (LNM) and high-volume LNM (hvLNM) in papillary thyroid microcarcinoma (PTMC) with di ameter ≤0.5 cm.Methods PTMC patients who received surgical treatments in Peking Union Medical College Hospital from Nov.2013 to Nov.2014 were reviewed.Patients were allocated into the ≤0.5 cm group and (0.5-1)cm group according to tumor diameter.Clinical and pathological features were assessed and compared.Risk factors of LNM and hvLNM were also assessed through univariate and multivariate analysis.Results 1414 patients were enrolled,of which 315 patients (22.3％) were in the ≤0.5 cm group.76 LNM (24.1％) and 9 hvLNM (2.9％) were detected in the ≤0.5 cm group.There was significantly less capsule invasion (14.3％ vs 25.0％,P＜0.05),LNM (24.1％ vs 39.8％,P＜0.05) and hvLNM (2.9％ vs 7.9％,P＜0.05) in ≤0.5 cm group than in (0.5-1)cm group.In univariate analysis,patients aging ＜40 years old were more likely to have LNM than those older than 40(38.0％ vs 20.1％,P＜0.05),while male patients tended to have more LNM than female (32.4％ vs 21.9％,P=0.073).No risk factors were identified for hvLNM.In multivariate analysis,multifocality and younger than 40 years old were the independent risk factors of LNM (OR=2.082 and 2.899,P＜0.05),while male tended to be the independent risk factors of LNM (OR=l.807,P=0.058).No independent risk factors was identified for hvLNM.Conclusions A certain proportion of PTMC patients are with tumor diameter ≤0.5 cm,who have lower risk of LNM and hvLNM.Dynamic observation may be an option,especially in older ≥40 years old),unifocal and female patients.