Endocrine Abstracts

Background: Differentiated thyroid cancer is the most prevalent thyroid cancer subtype, accounting for more than 95% of cases. Autoimmune thyroiditis, a frequent autoimmune disease, is reported in 25-30% patients with nodular goiter, according to the literatures. Differentiated thyroid cancer is associated with less aggressive disease and better outcome in patients with coexisting thyroid autoimmunity, but the studies already published revelead discordant data.

Aim: To observe the characteristics of patients diagnosed with differentiated thyroid carcinoma associated with autoimmune thyroiditis admitted to the Nuclear Medicine Department.

Methods: We present a retrospective analysis of our patients with differentiated thyroid cancer with coexisting thyroid autoimmunity who were evaluated from January1 to December 31, 2023 in a tertiary Nuclear Medicine Department - Oncologic Center Sanador, Bucharest. The pre- and post-operative thyroid function tests, ultrasound, histological exams as well as clinical history and examination were evaluated.

Results: 30 out of 103 patients hospitalized in our department with indication for radioactive iodine therapy had an association of autoimmune thyroiditis with differentiated thyroid cancer. Only two patients (ages 37 and 68) were males, whereas the remaining 28 were women (26 to 71 years). Preoperative the majority of patients (26 out of 30) were euthyroid, 3 had hypothyroidism, and one had autoimmune thyroiditis with the onset of hyperthyroidism. We registered one case of follicular carcinoma and 29 cases of papillary thyroid carcinoma, associated with autoimmune thyroiditis. Multifocality was observed in 40% of cases. 11 patients had lymph node metastases, with N stage: pN1a -5 patients and pN1b – 6 patients. According to ATA guidelines, our patients were divided as follows: 11 low-risk, 12 intermediate-risk, and 7 high-risk. At the moment of the admission in our Departement the Anti-thyroglobuline antibodies (Tg- Ab) remained elevated in 19 individuals (63.3%), with average values of 677 Ui/ml (35.7 to 3014 UI/ml). Despite being in the high-risk category with nodal involvement, the patients with very high values of Anti-thyroglobulin antibodies (>1000 UI/ml) had a stimulated thyroglobulin level below 1 ng/ml.

Conclusion: The association of autoimmune thyroiditis and differentiated thyroid cancer had lead to better prognostic. Most of our patients were low- and intermediate-risk, necessitating low doses of iodine therapy. More extensive studies are needed to establish a guideline for this subgroup of patients.