Recurrence Factors and Characteristic Trends of Papillary Thyroid Cancer over Three Decades

BACKGROUND: The prevalence of thyroid cancer is rising worldwide. Although thyroid cancer has a favorable prognosis, up to 20% of patients experienced recurrent disease during the follow-up period. The present study aimed to examine the trend of incidence and factors associated with recurrence and outcomes of papillary thyroid cancer (PTC) in Thai patients over the last 30 years. METHODS: We reviewed the clinical data of all patients with PTC who were treated between 1987 and 2019 at Theptarin Hospital. Clinical characteristics, epidemic trend, factors associated with the persistence/recurrence of the disease, overall disease-specific survival rate, and overall disease-free survival rate were analysed. RESULTS: A total of 235 patients with PTC who were registered between 1987 and 2019 were reviewed. The mean age was 42.5 ± 14.3 years, with a mean follow-up of 9.5 years. Papillary thyroid microcarcinoma (PTMC) was consistently increased and accounted for 21.4% (50/235) of total cases. The American Thyroid Association (ATA) risk stratification was high in 24% of all PTMCs in the last decade, and 16.0% of these patients experienced local recurrence during the follow-up period. Coexistence with Hashimoto's thyroiditis (HT) was found in one-fifth of the patients with PTC and was correlated with a low recurrence rate (HR: 0.16, P=0.013). Only age ≥55 years associated with the persistence/recurrence of the disease. The overall disease-free survival and disease-specific survival rates were 77.4% and 98.3%, respectively. CONCLUSIONS: The prognosis of PTC is generally considered favorable. However, approximately one-fourth of patients with PTMC demonstrated more aggressive clinical behavior, particularly in the last decade of the study. Coexistence of HT contributed to a better prognosis.