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

Abstract

Purpose: Tumor size at diagnosis has been widely used as a major mortality risk factor in risk stratification of DTC. 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 four 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 >4cm was associated with adverse clinico-pathologic 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 (> 4cm) 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 DTC patients, regardless of BRAF mutational status.