Outcome of papillary thyroid microcarcinoma: Study of 1,990 cases.

The present study examines the requirement of prophylactic neck node dissection in papillary thyroid microcarcinoma (PTMC) patients by analyzing high-risk factors of neck lymph node metastasis in PTMC. The clinical pathological data was a review of 1,990 patients diagnosed between January 2013 and January 2014. The data included information on patient gender, age, tumor size, multifocal, tumor pathological staging, bilateral thyroid cancer, the subtypes, BRAF (V600E) mutation, human telomerase reverse transcriptase (hTERT), extrathyroidal invasion and neck lymph node metastasis. The univariate analysis (χ(2) test) showed that a number of factors were significantly associated with neck lymph node metastasis in PTMC (P<0.05): Male gender, aged <45 years, extrathyroidal invasion, bilateral thyroid cancer, various subtypes (package type, follicular variant, diffuse sclerosing variant, eosinophils, tall cell and column variant), BRAF (V600E) mutation-positive, hTERT mutation-positive, pt3/4 and multifocality. The multivariate analysis (regression binary logistic) showed that the male gender, <45 years, tumor size >5 mm, extrathyroidal invasion, bilateral thyroid tumors, multifocality, BRAF (V600E) mutation-positive, hTERT mutation-positive and pt3/4 are associated with the neck lymph node metastasis in PTMC (P<0.05). These paired analysis results show that the subtypes of PTMC with tumor size >5 mm is more common than the specific types of PTMC in which the tumor is ≤5 mm in neck lymph node metastasis. The neck lymph node metastasis incidence of the >45 years age group patients without high-risk factors in PTMC is 8.13 and 6.80%, respectively. In conclusion, PTMC patients with high-risk factors only are recommended to undergo a prophylactic lymph node dissection.