[Influencing factors and predictive model development for contralateral central lymph node metastasis in unilateral papillary thyroid microcarcinoma].

<b>Objective:</b> To investigate the influencing factors for contralateral central lymph node metastasis (CLNM) in unilateral papillary thyroid microcarcinoma (PTMC) and develop a predictive model. <b>Methods:</b> The clinical data from 336 patients with unilateral PTMC who were admitted to Sichuan Cancer Hospital between May 2021 and September 2022 were retrospectively analyzed. The patients were randomly assigned into a training set (235 cases) and a validation set (101 cases) in a 7∶3 ratio by computer. Univariate logistic regression analysis was performed to screen for potential influencing factors related to contralateral CLNM. Subsequently, a stepwise multivariate logistic regression was used to develop a predictive model for contralateral CLNM and a nomogram was established. The discrimination, calibration, and clinical utility of the model were evaluated by receiver operating characteristic (ROC) curve, Hosmer-Lemeshow test, and decision curve analysis, respectively. <b>Results:</b> A total of 336 patients aged (43.4±12.0) years were included, with 71 males and 265 females. Multivariate logistic regression analysis indicated that age (>55 years: <i>OR</i>=0.24, 95%<i>CI</i>: 0.07-0.87, <i>P</i>=0.030), lateral neck lymph node metastasis (<i>OR</i>=1.98, 95%<i>CI</i>: 1.01-3.89, <i>P=</i>0.046), ipsilateral lymph node metastasis (<i>OR</i>=3.12, 95%<i>CI</i>: 1.60-6.07, <i>P</i><0.001), and pre-laryngeal lymph node metastasis (<i>OR</i>=2.92, 95%<i>CI</i>: 1.14-7.48, <i>P=</i>0.025) were significant influencing factors for contralateral CLNM. Based on the multivariate logistic regression results, a predictive model and corresponding nomogram were constructed. The area under the ROC curve (AUC) was 0.76 (95%<i>CI</i>: 0.69-0.83) in the training set and 0.72 (95%<i>CI</i>: 0.61-0.84) in the validation set. The Hosmer-Lemeshow test demonstrated good calibration (training set: χ²=5.717, <i>P</i>=0.335; validation set: χ²=1.354, <i>P=</i>0.716). Decision curve analysis showed that the model provided a net clinical benefit when the predicted risk threshold ranged from 0.12 to 0.67 in the training set and from 0.01 to 0.50 in the validation set. <b>Conclusions:</b> The current study indicates that age, lateral neck lymph node metastasis, ipsilateral lymph node metastasis, and pre-laryngeal lymph node metastasis are significant influencing factors for contralateral CLNM in unilateral PTMC. The predictive model developed using these factors demonstrates good discrimination, calibration, and clinical utility.