Differentiated Thyroid Cancer Recurrence and Mortality Prognostic Factors: A Retrospective Cohort Study on 350 Adult Patients.

INTRODUCTION: Differentiated thyroid cancer (DTC) accounts for the most common types of thyroid cancer. The aim of the present study was to investigate the factors associated with recurrence and mortality after thyroidectomy in patients with diagnose of DTC in Hamadan, Iran. MATERIALS AND METHODS: In this retrospective cohort study, 350 patients over 18 years old who underwent total thyroidectomy and ablation with radioactive iodine (RAI) and had DTC based on pathology and followed up for ten years were studied. The univariate and multivariate logistic regression was used for determining the risk factors of recurrence and mortality of DTC at a significance level of 0.05. SPSS software (Version 26) was applied to analyze the data. RESULTS: In the present study, 16.6% of the participants were male and 83.4% were female with a mean age of 40.7 ±14.7 years. Recurrence and mortality rates were obtained to be 26.9% and 4.9 %, respectively. Overall, the risk of recurrence and death was significantly higher in older age, men, smokers, tumors larger than 4 cm and regional lymph node (p<0.05). For each additional year of life, the risk of recurrence and death increased by 4% and 9%, respectively (P =0.001 and p<0.001). Recurrence in men were 5.111 times more likely than women (p<0.001). A 6.002-fold increase in the risk of death was associated with smoking (P=0.008). CONCLUSION: Due to the high prevalence of DTC and on the other hand the good prognosis of this type of cancer, timely diagnosis and identification of risk factors of recurrence and death are very important.