Abstract: Background and purpose: Chronic lymphocytic thyroiditis (CLT) is a common autoimmune inflammation. The aim of this present study was to determine the relationship between CLT and the response of patients with differentiated thyroid carcinoma (DTC) who received surgery and radioactive iodine (¹³¹I) treatment for thyroid carcinoma. Methods: We retrospectively analyzed 128 patients who received initial treatment for thyroid disease at Peking Union Medical College Hospital from 2014 to 2016. Data of the participants with histologically confirmed DTC were analysed according to the presence (CLT1) or absence (CLT0) of concurrent CLT. One-way analysis, chi-square test and rank-sum test, Mann-Whitney test and multivariate analyses were used to evaluate the clinicopathological features. Correlation analysis was conducted between response to ¹³¹I and the presence or absence of concurrent CLT. The response was evaluated between two groups according to 2015 American Thyroid Association (ATA) response system. Results: Of the 128 patients, smaller tumor size and a greater female preponderance were noted in the patients with CLT compared with those without CLT (P=0.028, P=0.011, respectively). There was no significant difference in age, multifocality, stages of lymph nodes, capsular invasion and TNM classification system between the groups for DTC during 24-month mean follow-up period. There was no significant difference in response between two groups. The excellent response (ER) was 72.7%(40/55) and 68.5%(50/73), respectively. Indeterminate response (IR) was 14.5%(8/55) and 13.7%(10/73), respectively. Biochemical incomplete response (BIR) was 3.6%(2/55) and 6.8%(5/73), respectively. Structural incomplete response (SIR) was 9.1%(5/55) and 10.9%(8/73), respectively. Meanwhile, there was no correlation between response and the presence or absence of CTL (P=0.519). Conclusion: Our results do not support the hypothesis that CLT is associated with the response to ¹³¹I treatment for DTC patients.

Key words: Differentiated thyroid carcinoma, Lymphocytic thyroiditis, Response, ¹³¹I therapy