Risk factors predictive of cervical lymph node metastasis in papillary thyroid microcarcinoma.

e18091 Background: Papillary thyroid microcarcinoma(PTMC) is defined as a papillary thyroid carcinoma(PTC) measuring less than or equal to 10mm in its greatest diameter.It has the highest incidence among all thyroid carcinomas. However, the clinical characteristics and risk factors predictive of cervical lymph node metastasis in PTMC have not yet been fully elucidated.Our study aimed to investigate the clinicopathological characteristics for PTMC and to identify the risk factors predictive of cervical lymph node metastasis in PTMC.This study was the Medical Science Research Project of Hebei Province (NO.20210957). Methods: We retrospectively reviewed the medical records of 714 pathologically proven conventional PTMC patients who underwent lobectomy or total or near-total thyroidectomy and central neck dissection(CND),with or without lateral neck dissection(LND) in our hospital between January 2019 and December 2020.The data were analyzed in relation to age at diagnosis, gender, tumor size,capsular invasion,multifocal tumor,tumor location,and lymph node metastasis(LNM) that includes central lymph node metastasis(CLNM) and lateral lymph node metastasis(LLNM).Logistic regression model was used to investigate the risk factors for LNM in PTMC.All analyses were performed with STATA 16. Results: There were 714 patients with PTMC, consisting of 491(68.8%) women and 223 (31.2%) men.Among them,331(46.4%) were≥55 years old,and 383(53.6%) were < 55 years old. 256 patients(35.9%) with tumor diameter≤5mm,and 458 patients(64.1%) with tumor diameter > 5mm.Among all patients, 211(30.0%) had multifocal,capsular invasion,566(79.0%) had multiple lobes,and 20(2.8%) had hashimoto's thyroiditis.CLNM occurred in 438(61.3%),while LLNM was found in 219(30.6%).The univariate analysis showed that male gender,age＜55 years,tumor size＞5mmtumor location in the lower third of the thyroid,multifocal,capsular invasion and bilateralism were significantly associated with CLNM.Multivariate analysis showed that the capsular invasion,tumor size＞5mm,multifocal,tumor location in the lower third of the thyroid were independently correlated with CLNM.In addition,univariate analysis showed that tumor size＞5mm,tumor location in the superior pole of thyroid,multifocal,capsular invasion, bilateralism and CLNM were associated with LLNM.However,multivariate analysis showed that tumor location in the superior pole of thyroid,capsular invasion,tumor size＞5mm,and CLNM were independently correlated with LLNM. Conclusions: Capsular invasion,tumor size＞5mm,multifocal,and tumor location in the lower third of the thyroid predict increased CLNM in PTMC patients.The possibility of LLNM should be carefully evaluated for these patients with tumors located in the upper pole of the thyroid gland,capsular invasion,tumor size＞5mm,and CLNM. Clinical trial information: 20210957 .