Correlates of Recurrence-Free Survival in Papillary Thyroid Carcinoma: A Cohort Study in an Iranian Population

Objective: Papillary thyroid carcinoma (PTC) is considered differentiated and has a good prognosis; however, the patient's survival differs from clinicopathological risk factors. This study is meant to assess factors predicting recurrence-free survival. Material and Methods: In this longitudinal study, we examined a cohort of 208 patients with PTC from 1977 to 2020. Patients who underwent total thyroidectomy entered the study. Thyroidectomy was considered the primary event, while the endpoint of the study was recurrence-free survival. A multivariate and univariate Cox regression test was used to identify independent risk factors in recurrence-free survival. Results: The 5-year recurrence-free survival was 90.5% [95% confidence interval (CI): 84.7-96.46]. Multiple regression models displayed that gender [p=0.01 hazard ratio (HR): 2.21, 95% CI 1.20-4.05] and tumor size (p=0.02 HR: 1.93, 95% CI 1.10-3.38) were the most significant factors influencing recurrence-free survival. The median recurrence-free survival among our patients was 12 years. According to the Kaplan-Meier tests, 5 and 10-year recurrencefree survival was 90.5% (95% CI: 84.7-96.46) and 51.7% (95% CI: 41.26-62.26), respectively. The median recurrence-free survival of the tumor was 24 years in tumors <1 cm and ten years in tumors in the range of 1-3.99 cm and ≥4 cm (p=0.02). Conclusion: The 5-year recurrence-free survival was 90.5% longer in women and those with tumors less than 1 cm. Tumor size and gender may affect the risk of recurrence/persistent disease.