[Risk factors for contralateral central lymph node metastasis in unilateral papillary thyroid carcinoma].

Objective: To explore the risk factors for contralateral central lymph nodes (Cont-CLNs) metastasis of unilateral papillary thyroid carcinoma (PTC) and to guide the decision-making of clinical surgical scope. Methods: The data of 362 patients who underwent total thyroidectomy and bilateral central lymph node dissection at the Sichuan Cancer Hospital from September 2020 to April 2022 and were confirmed as unilateral PTC by postoperative pathology were retrospectively analyzed. Among them, 87 were male and 275 were female, aged from 11 to 76 years. According to whether presence of Cont-CLNs metastasis, they were divided into the metastasis group (115 cases) and the non-metastasis group (247 cases). The relationship between the demographic characteristics, clinicopathological characteristics and other indicators of the two groups of patients and their metastases of Cont-CLNs was analyzed. Univariate analysis, multivariate logistic regression analysis and receiver operating characteristic (ROC) curve analysis were used to screen the risk factors for Cont-CLNs metastasis. Postoperative follow up was performed in the patients. Results: Univariate analysis showed that age, gender, combined Hashimoto's thyroiditis, extranodal invasion, pretracheal and prelaryngeal lymph node metastasis, ipsilateral central lymph nodes (Ipsi-CLNs) metastasis on the affected side, lateral cervical lymph node metastasis on the affected side, lesion location, and tumor diameter were associated with Cont-CLNs metastasis (all P values<0.05). Multivariate revealed that: each of male gender, Ipsi-CLNs metastasis, pretracheal and prelaryngeal lymph node metastasis, cancer focus location in the isthmus, and unilateral glandular lobe combined with isthmus was an independent risk factor for Cont-CLNs metastasis. For predicting the metastasis risk of Cont-CLNs, the optimal critical value of the number of metastasized Ipsi-CLNs was 2.5, and the area under the ROC curve (AUC) was 0.700; the optimal cut-off value of the number of metastasized pretracheal and prelaryngeal lymph nodes was 1, with an AUC of 0.681. The AUC of gender was 0.630, and the AUC of the cancer lesion location was 0.545. Multivariate ROC curve analysis for Cont-CLNs metastasis based on gender, the number of metastasized Ipsi-CLNs, the number of metastasized pretracheal and prelaryngeal lymph nodes, and the location of cancer foci showed an AUC of 0.794. The patients were followed up until January 2025. Excluding 3 cases with hoarseness caused by recurrent laryngeal nerve invasion before the operation and 3 cases with resection and reconstruction of invaded recurrent laryngeal nerves discovered during the operation, there were no patients with permanent recurrent laryngeal nerve palsy after the operation. There were 3 cases with postoperative permanent hypoparathyroidism. There no patients with postoperative recurrence. Conclusion: Risk factors for Cont-CLNs metastasis include male sex, Ipsi-CLNs metastasis, pretracheal and prelaryngeal lymph nodes metastasis, and tumor location in the isthmus or unilateral lobe plus isthmus. In unilateral PTC with the risk factors, Cont-CLNs dissection may be considered.