Extrathyroidal extension and cervical node infiltration are associated with recurrences and shorter recurrence-free survival in differentiated thyroid cancer: a cohort study.

Background: Differentiated thyroid cancer has excellent overall survival. However, around 20% of patients experience recurrent diseases after a certain time of follow-up. Therefore, identification of risk factors for recurrence is necessary to adjust treatment and surveillance planning.

Methods: A retrospective study was conducted of 312 patients with differentiated thyroid cancer who received surgery with and without adjuvant treatment. Clinical and pathological risk factors were analyzed for recurrences.

Results: After median follow-up of 57 months, 109 of 312 patients (34.9%) developed recurrences. Extrathyroidal extension and positive cervical nodes were significantly associated with recurrences (OR = 2.449, 95%CI:1.260-4.760, P = 0.008 and OR = 3.511, 95%CI:1.860-6.626, P < 0.001; respectively). Lympho-vascular invasion (LVI) and tumor multifocality were also associated with increased risk of recurrence (OR = 2.577, 95%CI:1.380-4.812, P = 0.003 and OR = 1.602, 95%CI:1.001-2.495, P = 0.050; respectively). Using multivariable regression, only older age and tumor infiltration to the lymph nodes were significantly associated with recurrences (OR = 2.227, 95%CI:1.037-4.782, P = 0.040 and OR = 2.966, 95%CI:1.470-5.986, P = 0.002; respectively). In addition, T4, cervical lymph node infiltration, older age, and LVI were associated with shorter recurrence-free survival.

Conclusion: Recurrence rates in our study population are relatively high. Extrathyroidal extension, positive neck lymph node, and older age were associated with recurrence risks of well differentiated thyroid cancers.