Value of dissection of lymph nodes posterior to the right recurrent laryngeal nerve in patients with cN papillary thyroid carcinoma.

[BACKGROUND] Tumor metastasis to lymph nodes posterior to the right recurrent laryngeal nerve (LN-prRLN) is a main cause of disease recurrence in patients with papillary thyroid carcinoma (PTC), which may increase the risk of recurrence and secondary surgery, and the disruption of normal anatomical relationships during secondary surgery increases the risk of laryngeal nerve injury and hypoparathyroidism. However, controversy remains as to whether the dissection of LN-prRLN is required in cN PTC patients. The purpose of this study is to explore the factors associated with LN-prRLN metastasis in patients with cN PTC and the need for LN-prRLN node dissection in patients with cN PTC who undergo right central compartment dissection.

[METHODS] The clinical data of 290 patients with cN PTC who received radical thyroid cancer surgery from December 2019 to March 2022 at our center were retrospectively analyzed. All the patients underwent thyroid lobectomy and right central lymph node dissection (CLND), along with other treatments. SPSS 26.0 statistical software was used for the analysis. The measurement data were compared using the rank-sum test, and the count data were compared using the chi-square test.

[RESULTS] LN-prRLN metastasis was detected in 65 (22.4%) of the 290 cN PTC patients. The metastasis sites included level VIa (51.72%), the left central compartment (22.76%), and the prelaryngeal compartment (8.97%). The univariate analysis revealed that tumor multifocality, a tumor diameter >1 cm, capsular invasion, LN metastasis in the left central compartment, and level VIa positivity were influencing factors of LN-prRLN metastasis in PTC patients. The logistic regression analysis showed that a tumor diameter >1 cm (OR =2.897, 95% CI: 1.630-5.147, P<0.001), LN metastasis in the left central compartment (OR =3.724, 95% CI: 2.039-6.801, P<0.001), and level VIa (OR =3.405, 95% CI: 1.846-6.281, P<0.001) positivity were independent risk factors of LN-prRLN metastasis in PTC patients.

[CONCLUSIONS] The high-risk factors of LN-prRLN metastasis in cN PTC patients include a large tumor (a diameter >1 cm), lymph node metastasis in the left central compartment, and lymph node metastasis in level VIa. For patients with cN PTC undergoing right CLND, with high-risk factors of LN-prRLN metastasis, LN-prRLN dissection is recommended.

[KEYWORDS] Papillary thyroid carcinoma (PTC); lymph nodes posterior to the right recurrent laryngeal nerve (LN-prRLN); central compartment lymph node dissection; risk factor.