Endocrine Abstracts

Introduction: Some studies suggest a possible link between autoimmune thyroid disease (AITD) and thyroid cancer (TC). However, existing data is inconsistent, and no consensus exists regarding this question.

Objective: The aim of this study was to analyze the association between TC and AITD, namely Hashimoto’s thyroiditis (HT) and Graves’ disease (GD).

Methods: We conducted a retrospective and observational study of all patients who underwent thyroid surgery (lobectomy or total thyroidectomy) between January 2020 and September 2022 at our center. Patients were diagnosed with AITD if they had at least one positive thyroid antibody (TPOAb, TgAb and/or TRABs) or if they had lymphocytic thyroiditis on histology. Statistical analysis was done using SPSS Statistics v.29.0. A P-value <0.05 was considered as statistically significant.

Results: We analyzed a total of 695 patients. 145 patients were excluded due to lack of data regarding the diagnosis of AITD. The 12 patients diagnosed with Non-invasive Follicular Thyroid Neoplasm with Papillary-like Nuclear Features (NIFTP) were also excluded. The average age at the time of surgery of the 538 patients included was 55.8 ± 15.1 years. There were 456 women (84.8%) and 82 men (15.2%). Most patients did not have AITD (61.0% vs. 39.0%) and had a benign histology (66.9% vs. 33.1%). We identified 171 patients (31.8%) with HT and 39 patients (7.2%) with GD. We found no statistically significant difference between the prevalence of TC in patients with or without AITD (33.8% vs. 32.6%; P=0.393). Also, no statistically significant difference was found in terms of occurrence of TC in a subanalysis of subjects with HT vs. subjects without AITD (38.6% vs. 32.6%; P=0.18). In the subgroup of patients with GD, there was a significantly lower percentage of malignancy than in patients without AITD (12.8% vs. 32.6%; P=0.01).

Conclusion: In this study, there was no positive correlation between the presence of AITD and the occurrence of malignant disease, contrary to what is suggested in some studies published in the literature. On the other hand, the malignancy rate was significantly lower in patients with GD compared to patients without thyroid AITD; this association may be due to the fact that, in most cases, the surgical indication in patients with GD is the treatment of hyperthyroidism and not the presence of a suspicious nodule. This reinforces the need for robust studies to clarify the possible role of thyroid autoimmunity in thyroid carcinogenesis.