With the increasing incidence of papillary thyroid cancer (PTC), it is important to risk-stratify patients who may have a more aggressive tumor biology. The present study aimed to evaluate the risk factors for lymph node metastasis (LNM) in patients with PTC, which may provide a significant reference for clinical diagnosis and treatment. In total, 1,045 patients with PTC [313 with PT microcarcinoma (PTMC) and 732 with non-PTMC] between August 2016 and August 2019 were investigated. The B-type Raf kinase (BRAF) V600E mutation was tested in all samples. The clinical data (sex, age, tumor location, sample type and pathological features) were retrospectively analyzed. Logistic regression analysis was performed to evaluate independent risk factors for LNM. A total of 181/313 (57.8%) PTMC cases and 145/732 (19.8%) non-PTMC cases had a BRAF V600E mutation. In the PTMC cases, significant differences in sex and sample type were identified (BRAF V600E mutation vs. wild-type). In the non-PTMC cases, significant differences in sex and age were identified (BRAF V600E mutation vs. wild-type). Female sex and tumor diameter ≤1 cm were significant independent predictors of LNM in PTC. In PTMC, female sex was a significant independent predictor of LNM. A bilateral tumor was an independent protective factor for LNM in PTC, PTMC and non-PTMC. The BRAF V600E mutation rate of ultrasound-guided fine-needle aspiration cytology was higher compared with FFPE in PTMC (P=0.018). In contrast to previous studies, the results of the present study suggested that being female and having a tumor of diameter ≤1 cm were risk factors for LNM, and that the BRAF wild-type of PTMC may be more aggressive than other types. Notably, the position of the tumor in the bilateral thyroid was also an independent protective factor for LNM. Therefore, ultrasound-guided fine-needle aspiration should be recommended for gene analysis (BRAF V600E) in PTMC. In addition, clinicians should consider an individualized treatment according to gene mutations, sex, age, tumor size and the location of the tumor, in order to achieve an improved therapeutic efficacy.

Background: With the increasing incidences of papillary thyroid cancer(PTC), it is important to risk-stratify patients who may have more aggressive tumor biology. This study aimed to evaluate the risk factors for lymph node metastasis with PTC in Southwest China Patients which may provide a substantial reference for clinical diagnosis and treatment. Methods: 1045 PTCs (313 PTMC and 732 non-PTMC) between August 2016 and August 2019 were examined totally (including one Tibetan). BRAF V600E mutation was tested in all samples. The clinical data (gender, age, tumor location, sample source and pathological features) were retrospectively analyzed. Logistic regression analysis was performed to evaluate independent risk factors for LNM. Results: 181 out of 313 PTMC cases (57.8%), 145 out of 732 non-PTMC cases (19.8%) had BRAF V600E mutation, the Tibetan had a double mutation of BRAF L597Q and V600E in two separate lesions. In PTMC, significant difference in gender and sample source was found (BRAF V600E mutation vs. wild-type). In non-PTMC, significant difference in gender was found (BRAF V600E mutation vs. wild-type). The female (OR=1.952; 95% CI= 1.373-2.774; P= 0.00), age (31-59 years) and diameter of tumor ≤1cm (OR=3.273; 95% CI= 2.417-4.432; P=0.000) were significant independent predictors of LNM in all PTCs. In PTMC, the female (OR= 3.002; 95% CI= 1.654-5.446; P= 0.00) was a significant independent predictor of LNM. The tumor in left and right lobes simultaneously was an independent protective factor of LNM in each group (PTCs: OR=0.287; PTMC: OR=0.170; non-PTMC: OR=0.441, respectively). The BRAF V600E mutation rate of US-FNAC was much higher than FFPE in PTMC (P=0.018). Conclusions: Unlike previous research, our findings suggested that the female patients and diameter of tumor ≤1cm were risk factors for LNM and the BRAF V600E wild-type of PTMC might be more aggressive than others. Interestingly, the position of tumor in bilateral thyroid simultaneously was an independent protective factor for LNM. The US-FNA should be recommended for gene analysis (BRAF V600E) in PTMC. The BRAF L597Q mutation may be an independent aggressive factor in the Chinese Tibetan population. Hence, clinicians should consider an individualized treatment according to gene mutation, gender, age, tumor size and location of tumor in order to achieve a better therapeutic efficacy.