Abstract:Objective To explore the clinical characteristics of differentiated thyroid cancer (DTC) combined with Hashimoto's thyroiditis (HT), and to compare the efficacy of different surgical methods. Methods A retrospective analysis was conducted on data from 692 patients with DTC initially treated at Liaoning Cancer Hospital & Insititute from January 2018 to May 2019. The patients were divided into DTC group (n=485) and DTC combined with HT (DTC-HT) group (n=207). Clinical characteristics and postoperative complications were compared between two groups. Results There were statistically significant differences between two groups in terms of gender, microcarcinoma, multifocality, thyroid invasion, neck lymph node metastasis, reoperation, and thyroid peroxidase antibody (P<0.05). The proportion of patients with no blood flow signal in the DTC-HT group was higher than that in the DTC group (47.8% vs 39.0%, χ2=4.684，P=0.030). There was no statistically significant difference in drainage volume at the first day after operation, transient hypocalcemia, and temporary hoarseness between total thyroidectomy and non-total thyroidectomy patients in the DTC-HT group (P>0.05). Conclusion Patients with DTC combined with HT often present with microcarcinomas and multifocality, mainly females. After surgery, residual thyroid tissue may reveal new lesions, often necessitating a second surgery. Planned total thyroidectomy with ipsilateral central lymph node dissection should be considered.