The effect of central lymph node dissection on the prognosis of cN0 papillary thyroid microcarcinoma: a mid-term follow-up study

BACKGROUND: To investigate the effect of central lymph node dissection on the prognosis of patients with papillary thyroid microcarcinoma (PTMC) without clinical lymph node metastasis (cN0). METHODS: According to the inclusion and exclusion criteria, 462 patients with cN0 PTMC underwent surgery in the Second Department of General Surgery, Zhongshan City People’s Hospital from January 1, 2007, to June 31, 2017. They were divided into two groups: the undissection group (262 cases) and the dissection group (170 cases). A comparison was made between the two groups in terms of postoperative complications, recurrences, metastases, etc., as well aslymph node metastasis risk factors in the central region of cN0 PTMC. RESULTS: There was no lymphatic leakage or death in all patients after the operation. In the dissection group, 64 cases (37.6%) of central lymph node metastasis were found after the postoperative pathological examination. The undissection group was followed up for (92 ± 28.7) months, and the dissection group was followed up for (86 ± 25.4) months (t=-2.165, P = 0.031). In the two groups, there were no lung metastases, bone metastases, or other distant metastases during the follow-up period. In the undissection group, there were 7 cases, while in the dissection group, there were just 2. Recurrence rates between the two groups did not differ significantly (χ(2) = 0.126, P = 0.169); Similarly, disease-free survival curves did not differ significantly (χ(2) = 2.565, P = 0.708). Hypoparathyroidism and Hypocalcemia also had no difference between the group. In comparison to the undissection group, the capsular invasion rate (P = 0.026), calcification rate(P < 0.001) incidence of postoperative hoarseness (P = 0.017), and hand and foot numbness rate (P < 0.001) were all considerably greater in the dissection group. Multivariate research revealed that capsular invasion (OR = 9.42, P = 0.002), multifocal (OR = 24.57, P < 0.001), and tumor diameter > 5 mm (OR = 5.46, P = 0.019) were the independent risk factors for central lymph node metastasis in cN0 PTMC. CONCLUSIONS: Thyroidectomy alone is safe for cN0 PTMC, but longer-term follow-up is still required for changes in central lymph nodes. For cN0 PTMC patients with tumor diameter > 5 mm, multifocal, and capsular invasion, central lymph node metastasis is more likely to occur. Comprehensive evaluation and individualized and precise treatment are essential.