The Prognostic Impact of Tumor Size and BRAF Mutational Status in Middle Eastern Differentiated Thyroid Cancer.

[CONTEXT] Tumor size at diagnosis has been widely used as a major mortality risk factor in risk stratification of differentiated thyroid cancer (DTC).

[OBJECTIVE] The current study was designed to analyze whether tumor size at diagnosis is a major prognostic factor in Middle Eastern DTC.

[METHODS] We conducted a comparative study of the relationship between tumor size at diagnosis and event-free survival (EFS) with respect to BRAF status in 1709 consecutive patients treated surgically for DTC. Patients were divided into 4 groups according to the size of tumor and BRAF mutation status: Group 1 (≤4 cm without BRAF mutation), Group 2 (≤4 cm with BRAF mutation), Group 3 (>4 cm without BRAF mutation), and Group 4 (>4 cm with BRAF mutation). Predictors of EFS were compared using the log-rank test and Cox proportional hazards models.

[RESULTS] Tumor size >4 cm was associated with clinicopathologic characteristics, such as older age, male gender, bilateral tumors, extrathyroidal extension, lymphovascular invasion, advanced tumor stage, and persistent/recurrent disease. Tumor size was also inversely associated with BRAF mutation. Both tumor size (>4 cm) and BRAF mutation were associated with EFS on univariate analysis. On subgroup analysis, larger tumor size was an independent predictor of EFS (Group 3 vs Group 1), irrespective of BRAF mutation status. Also, within the BRAF mutant tumors, larger tumor size was still an independent predictor of EFS (Group 4 vs Group 2).

[CONCLUSION] Tumor size is an independent predictor of EFS in Middle Eastern patients with DTC, regardless of BRAF mutational status.