OBJECTIVE: To study the prevalence of BRAF(V600E) mutations in small (≤ 2 cm) papillary thyroid carcinoma (PTC), explore the correlation with occult central nodal metastasis (CNM) of clinically-nodal negative (cN0) neck for small (≤ 2 cm) papillary thyroid carcinoma (PTC). METHOD: Primary tumor tissue (paraffin-embedded) from 72 patients with small (≤ 2 cm) cN0 PTC who underwent prophylactic central neck dissection (pCND) was tested for BRAF mutation. by nested PCR, the factors of lymph node metastasis such as clinicopathologic including tumor size, multifocality, extrathyroidal invasion, and BRAF mutations were analyzed. Prediction scores were generated using logistic regression models and BRAF was evaluated to see if it was a risk factor for CNM. RESULT: The prevalence of BRAF was 47.22% (34/72) while the rate of CNM was 36.11% (26/72). Univariate analysis showed that the risk factors of lymph node metastasis for cN0 PTC were significantly correlated with tumor size (P = 0.016), bilateral tumor (P = 0.010), multifocality (P = 0.026), extrathyroidal invasion (P = 0.024), and BRAF mutations (P = 0.041). Univariate analysis showed that tumor size (OR = 2.674, 95% CI = 1.702-3.997), multifocality (OR = 1.371, 95% CI = 1.065-2.087), extrathyroidal invasion (OR = 0.540, 95% CI = 0.396-0.794) and BRAF (OR = 1.647, 95% CI = 1.101-2.463) were risk predictors of CNM. CONCLUSION The incidence of central neck micrometastatic disease is 36.11% in patients with PTC deemed N0 preoperatively by clinical examination and ultrasound of the neck lymph nodes and intraoperatively by inspection of the central compartment. The factors of high risk of CNM included tumor size, multifocality, extrathyroidal invasion, BRAF mutations. When a patient has the risk factors of lymph node metastasis should be electived prophylactic CCND.
Axilla ; Carcinoma ; genetics ; Carcinoma, Papillary ; Humans ; Logistic Models ; Lymph Nodes ; Lymphatic Metastasis ; genetics ; Mutation ; Neck ; Neoplasm Micrometastasis ; diagnosis ; Neoplasm Staging ; Polymerase Chain Reaction ; Proto-Oncogene Proteins B-raf ; genetics ; Risk Factors ; Thyroid Cancer, Papillary ; Thyroid Neoplasms ; genetics

Objective To investigate the composition and pathological subtypes of thyroid cancer in patients with thyroid nodule surgery in Guiyang in recent 8 years, and to analyze their influencing factors. Methods A retrospective pathological analysis of 4 262 thyroid surgery cases in Affiliated Hospital of Guizhou Medical University during the 2009-2016 to investigate the proportion of thyroid cancer and pathological subtype. The iodine content of salt was reduced at the end of 2012 in Guiyang. 2009-2012 as the pre down-regulation group(n＝1 572), 2013-2016 as the after down-regulation group ( n＝2 690), then comparative analysis before and after the adjustment of the iodine content of salt composition of thyroid cancer and changes of pathological subtype was performed. Results From 2009 to 2016, the proportion of thyroid cancer were 17.08%, 17.52%,15.65%, 18.58%, 19.80%, 29.35%, 35.34%, and 48.33%, increased year by year (P＜0.05). Thyroid microcarcinoma were 2.14%, 4.74%, 3.40%, 3.65%, 3.80%, 7.03%, 9.10%, and 25.95%(P＜0.05). The constituent ratio of thyroid cancer after adjustment of salt iodine content was higher than before. Papillary thyroid carcinoma is the main pathological subtype before and after adjustment of salt iodine content. The proportion of female patients was higher than that of males. The age of patients with thyroid cancer after adjustmen was higher than before ( P＜0. 05). Conclusions In the past 8 years, the constituent ratio of thyroid cancer and thyroid microcarcinoma in Guiyang increased year by year. The reason may be related to the increase of radiation in the environment, the improvement of medical level and the higher detection rate of thyroid microcarcinoma. The relationship between iodine nutrition and thyroid cancer needs to be further studied.[Key words] Thyroid cancer; Thyroid microcarcinoma; Thyroid papillary carcinoma; Pathological type;Iodized salt; Iodine nutrition