Nomogram for predicting central lymph node metastasis in papillary thyroid microcarcinoma: A retrospective cohort study of 8668 patients

Introduction: The status of central lymph node metastasis (CLNM) is crucial to determining the surgical strategies for papillary thyroid micro carcinoma (PTMC). The objective of the study was to establish a nomogram to predict the possibility of CLNM in PTMC patients. Methods: A total of 8668 PTMC patients who underwent total thyroidectomy or lobectomy with central lymph node dissection (CLND) from 2006 to 2016 were retrospectively retrieved. Univariate and multivariate analysis were performed to examine risk factors associated with CLNM. A nomogram for predicting CLNM was established and internally validated. Results: Six variables significantly associated with CLNM were included in our model, these are age < 55 years (odd ratio [OR] = 1.779, 95% confidence interval [CI], 1.569-2.017; P < 0.001), male sex (OR = 1.718, 95% CI, 1.543-1.913; P < 0.001), tumor size 0.5-1.0 cm (OR = 1.985,95% CI, 1.761-2.238; P < 0.001), multi-focal lesions (OR = 1.263, 95% CI, 1.118-1.426; P < 0.001), extra thyroidal extension (ETE) (OR = 1.348, 95% CI, 1.092-1.664; P = 0.005) and lateral lymph node metastasis (LLNM) (OR = 5.135, 95% CI, 4.236-6.225; P < 0.001). The discrimination of the prediction model was 0.711 (95% CI, 0.700-0.722; P < 0.001). Conclusions: Based on the quantified risk stratification offered by our nomogram, clinicians might have a thorough discussion with PTMC patients during the both pre- and postoperative period. Prophylactic CLND and strict postoperative evaluation may be indicated when the patients have a high nomogram score.