The prognostic implication of skip metastasis to lateral neck in patients with papillary thyroid cancer

Background: Pre-operative detection of skip metastasis in papillary thyroid cancer (PTC) is significant in preventing recurrence. The study aimed to investigate the characteristics and prognosis of skip metastasis to lateral neck in PTC patients by a cross-sectional study. Methods: Between 2013 and 2016, 494 patients who underwent thyroidectomy for PTC and positive lateral lymph node metastases (LLNM) were retrospectively identified. Among them, we encountered 38 patients with skip metastasis, which was all confirmed by the histological examination. Recurrence/ persistence rates were analyzed during follow-up. To determine the risk variables, patients with different skip metastasis statuses were compared according on sonographic and clinicopathological factors. Results: Among the PTC patients with LLNM, 7.7% had skip metastasis. The most common distribution model of skip metastasis was 1 level (63.2%), and level III (71.1%) was most frequently involved. We discovered that skip metastasis was associated with tumors in the upper portion of the thyroid, and patients with pathological low-volume LLNM [<= 5 lymph nodes (LNs)] were more likely to have skip metastasis. Some 16.7% of patients with skip metastases who had a median follow-up of 45 months had recurrence or persistence. Recurrence/persistence-free survival rates at 3 and 5 years were 93.3% and 74.7%, respectively. The recurrence/persistence rate of PTC patients with skip metastasis was equal to those with LLNM (P=0.08). Conclusions: Particularly for patients who had tumors in the upper portion with low-volume LLNM, a thorough preoperative examination of the lateral LNs should be necessary. Skip metastasis is not uncommon in PTC patients with LLNM, and with appropriate treatment the prognosis is equal to that of those with LLNM.