Preoperative BRAF mutation has different predictive values for lymph node metastasis according to tumor size.

OBJECTIVE

To investigate whether BRAF mutation of papillary thyroid carcinoma (PTC) has different predictive values for regional lymph node (LN) metastasis according to tumor size.

STUDY

DESIGN

Prospective cohort study. Setting. A tertiary hospital.

SUBJECTS AND

METHODS

From January 2009 to August 2009, the authors prospectively enrolled 102 consecutive patients with unifocal PTC based on the findings of ultrasonography-guided fine-needle aspiration biopsy (FNAB). BRAF mutation was tested on preoperative FNAB specimens. Total thyroidectomy and bilateral central neck dissection (± lateral neck dissection) was performed for all patients. Among 102 patients, 71 who were confirmed to have unifocal PTC by the surgical pathology were finally selected. The 71 patients were classified into 3 groups according to their tumor size: group I, ≤0.5 cm; group II, >0.5 cm and ≤1 cm; and group III, >1 cm. LN metastasis was evaluated in the surgical specimen as a dependent variable. The authors investigated whether BRAF mutation is predictive of LN metastasis in each group.

RESULTS

Overall, BRAF mutation was a significant predictor of LN metastasis (P = .045). When patients were classified into 3 groups, frequency of LN metastasis increased with tumor size: 4.8%, 50.0%, and 66.7% (P < .001). However, the frequency of BRAF mutation was not different among 3 groups: 61.9%, 56.3%, and 72.2% (P = .536). BRAF mutation was predictive of LN metastasis only in group II (P = .026).

CONCLUSION

BRAF mutation of PTC may have differential predictive values for LN metastasis, according to tumor size.