Risk factors of cervical lymph node metastasis and distant metastasis in patients with primary squamous cell carcinoma of the thyroid: a population-based study

To analyze the risk factors associated with the occurrence of cervical lymph node metastasis (LNM) and distant metastasis (DM) in patients with primary squamous cell carcinoma of the thyroid (PSCCT). Clinical data of 96 patients with PSCCT from SEER database were obtained and analyzed by logistic regression for clinicopathological characteristics, including age, marital status, race, gender, tumor size (mm), extrathyroidal extension (ETE), multifocality, T stage, M stage and other indicators. Differences were considered statistically significant when P < 0.05. (1) Analysis of risk factors for the occurrence of cervical lymph node metastasis in patients with PSCCT: The results of univariate analysis showed that compared with patients without lymph node metastasis, patients with metastasis had a higher percentage of patients with the age ≥ 70 years old, tumor sizes greater than 40 mm, extrathyroidal extension, multifocal tumors, T4 stage and distant metastasis, the difference was statistically significant (P < 0.05). The results of multivariate analysis showed that multifocality and M stage were independent risk factors for the occurrence of LNM in PSCCT patients (P < 0.05). (2) Analysis of risk factors for the occurrence of distant metastasis in PSCCT patients: The results of univariate analysis showed that the percentage of patients who developed distant metastasis with age ≥ 70 years old, tumor size > 40 mm, T4 stage, and lymph node metastasis was higher than that of those who did not develop distant metastasis, and the difference was statistically significant (P < 0.05). The results of multivariate logistic regression analysis showed that cervical lymph node metastasis was an independent risk factor for the occurrence of distant metastasis in PSCCT patients (P < 0.05). (3) Relevant clinicopathologic features have not been found to be statistically significant with lung and bone metastasis, with P values greater than 0.05. Multifocality and M stage are independent risk factors for LNM in PSCCT patients, and cervical lymph node metastasis is an independent risk factor for distant metastasis in PSCCT patients. The findings of this study may provide guidance for individualized treatment plans for PSCCT patients.