Comparison of Long-Term Outcomes Between Ipsilateral and Bilateral Central Neck Dissection in Occult Contralateral Central Lymph Metastasis in Papillary Thyroid Carcinoma With Unilateral Lateral Neck Metastasis Using Propensity Score Matching

This study aimed to evaluate long-term prognosis of contralateral central neck dissection in papillary thyroid cancer (PTC) patients with ipsilateral lateral neck metastasis. We aimed to produce clinical evidence to help determine the extent of central neck dissection (CND) focusing on the separation between the ipsilateral and contralateral sides. A total of 708 PTC patients who underwent total thyroidectomy and concomitant ipsilateral or bilateral CND with ipsilateral lateral neck dissection (LND) were retrospectively included between January 1997 and December 2015 at a single institution. The median follow-up time was 89.7 months, the mean age was 44.7 years and the mean tumor size was 1.5 cm. Among the study population, 507 were female (71.5%) and 201 (28.5%) were male. Locoregional recurrence (LRR) was observed in 26 (7.9%) patients and 30 (7.9%) patients in the ipsilateral and bilateral CND groups, respectively. There were 6 (1.8%) contralateral recurrence cases in the ipsilateral CND group and 5 (1.3%) cases in the bilateral CND group. Male sex (adjusted HR = 1.857, p = 0.034), larger tumor size (adjusted HR = 4.298, p = 0.006), and more metastatic ipsilateral central lymph nodes (adjusted HR = 1.078, p = 0.014) significantly increased the risk of LRR. Ipsilateral CND only did not significantly increase the risk of LRR (adjusted HR = 1.110, p = 0.712). There were no significant differences in recurrence according to contralateral central neck dissection status after propensity score matching (p = 0.424), either. The incidence of hypocalcemia (p = 0.007) was higher in the bilateral CND group compared to the ipsilateral CND group. Surgeons may consider performing contralateral CND only for therapeutic purposes to reduce unnecessary complications.