Clinicopathological Findings Associated With Cervical Lymph Node Metastasis in Papillary Thyroid Microcarcinoma: A Retrospective Study in China

OBJECTIVE: The incidence of papillary thyroid microcarcinoma (PTMC) has increased sharply during the past decades. Yet, whether or not nodal dissection should be performed remains controversial. This article aims to assess the high-risk factors associated with cervical lymph node metastasis (LNM) in patients with PTMC, which may potentially guide clinical management decision-making. METHODS: Medical records of 449 PTMC patients who underwent thyroidectomy in our hospital from August 2016 to July 2017 were retrospectively reviewed. Clinical and pathological factors of the patients were anonymously extracted from the charts and analyzed. RESULT: The patients were classified into two subgroups according to maximum tumor size measured through post-surgical pathology: smaller PTMC group (≤5 mm) and larger PTMC group (>5 mm). Larger tumor size was found to be associated with a higher rate of LNM (P = .001), particularly central lymph node metastasis (CLNM) (P = .001). Tumor size was also associated with extrathyroidal tumor extension (ETE) (P < .001), bilateral lesions (P = .015), and BRAF(v600e) mutation (P = .004). LNM was found to be more common in older patients (>55 y) (P = .030), and those with multifocal cancer (P < .001). In PTMC patients with unilateral lesions without ETE, tumor size was not significantly associated with LNM (P = .121). CONCLUSIONS: For the PTMC population, tumor size was an independent risk factor for LNM, particularly for patients of old age (>55 y), and multifocality. However, in PTMC patients with unilateral lesions without extrathyroidal extension, tumor size was not related to the risk of LNM. These findings may potentially guide clinical decision-making in terms of cervical nodal dissection.