The association between BRAF V600E mutation of lymph node metastasis and its invasive characteristics in thyroid papillary carcinomas

Objectives: The BRAF V600E mutation in primary thyroid tumors appears to be associated with tumor aggressiveness and a worse prognosis in papillary thyroid cancer (PTC). However, little is known about the relationship between the BRAF V600E mutation in lymph node metastases (LNM) and pathological features of LNM.Our study aims to explore the relationship between the BRAF V600E mutation of LNM and its invasive characteristics in PTC.

Methods: A total of 248 PTC patients were enrolled in this study at Zhujiang Hospital of Southern Medical University from January 2014 to December 2017. The patients were histologically confirmed for PTC with cervical lymph node metastasis, examined for BRAF V600E in primary tumors and LNM and followed for a minimum of 6 months after iodine-131 (¹³¹I) therapy. Patients were excluded from the study if they had poor compliance, such as irregular follow-up or thyroid-stimulating hormone (TSH) suppressed therapy.

Results: Of the 248 patients, the BRAF V600E mutation frequency in primary thyroid tumors (83.9%) was slightly higher than that in LNM (80.2%, p = 0.022), and the intraclass correlation coefficient (ICC) was 0.826 (95% CI 0.782−0.862). There was a negative correlation between the BRAF V600E mutation in primary thyroid tumors and aggressive variants (OR = 0.146, 95% CI 0.022-0.987, p = 0.048). The BRAF V600E mutation in primary thyroid tumors and LNM was significantly negatively correlated to the size of the largest metastatic focus of LNM (OR = 0.073, 95% CI 0.008-0.698, p = 0.023 and OR = 0.076, 95% CI 0.007-0.818, p = 0.034, respectively). There is no relationship between the BRAF V600E mutation in LNM and the number of LNM, extranodal extension and fusion of LNM (p > 0.05).

Conclusions: We conclude that the BRAF V600E mutation in LNM may not be related to the invasive characteristics of LNM in PTC.