Therapeutic central lymph node dissection in papillary thyroid cancer: what is the optimal extent in unilateral nodal disease?

BACKGROUND: The optimal extent of central lymph node dissection (CLND) in patients with unilateral papillary thyroid cancer (PTC) and clinical nodal involvement (cN1a) confined to the ipsilateral central compartment remains controversial due to its potential risks, including permanent hypoparathyroidism and recurrent laryngeal nerve palsy. This study aimed to assess the prevalence of contralateral central neck recurrence following omission of contralateral prophylactic CLND. METHODS: A retrospective, single-center study was conducted, including patients with unilateral cN1a PTC who underwent ipsilateral CLND between 2010 and 2021. Exclusion criteria were: age < 18 years, prior neck surgery, non-papillary histologies, isthmus or pyramidal lobe tumors, T4b/M1 classification (AJCC 8th Ed.), R1-R2 resection status, bilateral multifocal disease, and nodal involvement limited to prelaryngeal and/or pretracheal chains. RESULTS: Seventy-five patients met the inclusion criteria, with a median follow-up of 61.6 (IQR: 34.95–85.18) months. Despite the presence of high-risk factors previously described for contralateral occult lymph node metastasis, including male sex, younger age, tumor size > 1 cm, aggressive histology, multifocal disease, lymphovascular invasion, > 5 metastatic central lymph nodes, and concomitant lateral neck nodal disease (cN1b), only 2/75 patients (2.7%) developed relapse. The 5- and 10-year contralateral central neck recurrence-free probabilities were both 97.2% (95% CI: 89.3–99.3%). Postoperative complications included transient hypocalcemia (12/75), permanent hypoparathyroidism (3/75), and recurrent laryngeal nerve injury, both transient (3/75) and permanent (1/75). CONCLUSIONS: Our findings suggest that restricting central neck dissection to the clinically affected side may be oncologically safe, minimizing complications associated with bilateral procedures.