Prognostic factors for recurrence of locally advanced differentiated thyroid cancer.

Background and Objectives To present treatment outcomes and prognostic factors for surgical management of locally advanced differentiated thyroid cancer (DTC). METHODS: Retrospective review of 70 patients in a single, tertiary referral institution was done. Clinical pathology characteristics were analyzed to investigate prognosticators, based on primary endpoints; locoregional recurrence alone (LRR), total recurrence (LRR or distant metastasis (DM)), and recurrence-free survival. RESULTS: Recurrent laryngeal nerve (n = 31) and trachea (n = 30) were most commonly invaded organs by tumor. At the mean follow-up of 81.7 months, LRR occurred in 15 patients and/or DM was detected in 15 patients (10 developed LRR and DM). By multivariate analysis, R1 resection (positive margin) and pN1b stage increased risk of LRR with a fold of 3.16 [95%CI 1.08-9.24, P = 0.03] and 5.92 [1.61-21.7, P = 0.007], respectively. Also, they increased risk of total recurrence with a fold of 3.04 [95%CI 1.26-7.31, P = 0.01] and 3.42 [95%CI 1.16-10.0, P = 0.02], respectively. Patients with pN1b stage showed better LRR-free survival than pN0/N1a stage (P = 0.03). Conclusions Along with careful preoperative evaluation of the extent of primary and neck disease, obtaining negative resection margin and aggressive neck management is critical to improve oncologic outcomes of locally advanced DTC.