Clinical outcomes after delayed thyroid surgery in patients with papillary thyroid microcarcinoma

Objective Active surveillance is an option for patients with papillary thyroid microcarcinoma (PTMC). However, the long-term clinical outcomes after delayed surgery remain unclear. We compared the long-term clinical outcomes of PTMC patients according to the time interval between initial diagnosis and surgery. Design and methods In this individual risk factor-matched cohort study, PTMC patients were classified into three groups according to the delay period: ≤6 months, 6–12 months and >12 months. Patients were matched by age, sex, extent of surgery, initial tumor size as measured by ultrasonography (US), and by the presence of extrathyroidal extension, multifocal tumors and central cervical lymph node metastasis. We compared the dynamic risk stratification (DRS) and the development of structural persistent/recurrent disease of patients. Results A total of 2863 patients were assigned to three groups. Their mean age was 50 years, 81% were female and 66% underwent lobectomy. The mean tumor size at the initial US was 0.63 cm. There were no significant differences in clinicopathological characteristics between groups after individual risk factor matching. Comparison of the DRS revealed no significant difference according to the delay period (P = 0.07). During the median 4.8 years of follow-up, there were no significant differences in the development of structural recurrent/persistent disease (P = 0.34) and disease-free survival (P = 0.25) between groups. Conclusions In PTMC patients, delayed surgery was not associated with higher risk of structural recurrent/persistent disease compared to immediate surgery. These findings support the notion that surgical treatment can be safely delayed in patients with PTMC under close monitoring.