Abstract A144: Clinical and morphological characteristics as a predictors of the development of radioiodine resistance in thyroid cancer

Abstract Relevance. Thyroid cancer, as in world practice, is a common disease in Kazakhstan. According to the Oncological Service of the Republic of Kazakhstan (RK), in 2023, this pathology is included in the list of the 10 most common cancers in women. Treatment of highly differentiated thyroid (DTC) cancer using radioiodine therapy is an effective method that helps eliminate residual thyroid tissue and potential tumor foci that can accumulate I-131. However, it should be noted that some patients develop resistance to radioiodine therapy. Currently, the risk factors for developing resistance to radioiodine therapy remain poorly understood. The aim of the study was to study the clinical and morphological risk factors for the development of radioiodine resistance in patients with highly DTC. Materials and methods of research. The design of the study is case-control. The study was conducted among patients treated at the radionuclide therapy department of the Centre for Nuclear Medicine and Oncology of RK. The primary information is collected on the basis of a single electronic database of the medical information system. For the analysis were included 630 patients who underwent treatment for thyroid cancer between January 2021 and December 2023. Of these, 373 medical records met the established criteria for inclusion in the study. The statistical analysis was performed using the SPSS 20.0 program. The results of the study. During the analysis of 373 patients, 60 were assigned to the main group with resistance to radioiodine therapy, and 313 were in the control group. When assessing the volume of surgery, total thyroidectomy with fascial-caseal excision of the neck tissue was performed for 58.3% of patients in the main group, characterized by resistance to radioiodine therapy, whereas in the control group, this volume of intervention was performed only in 29.1% (p< 0.001). The main histological types of thyroid cancer in the study groups were papillary cancer (74.5%) and follicular cancer (25.5%). The presence of microcarcinoma against the background of these histological types of cancer was found in 8 patients of the control group. The presence of distant metastases was significantly more common in the main group (23.3% vs 7.3%) compared with the control (p< 0.001). Conclusions. Based on the analysis, it can be concluded that, total thyroidectomy with lymph node dissection is statistically more often observed in patients with resistance to radioiodine therapy. However, surgical treatment itself is not a causal factor in the development of radioiodine resistance. Most likely, the expanded scope of surgery reflects a more aggressive course of the disease, which is initially associated with the risk of developing radioiodine-resistant forms of tumor. Histological examination data, detection of microcarcinoma, and the presence of distant metastases should be considered as clinical and morphological factors associated with the risk of developing resistance to radioiodine therapy in patients with highly differentiated thyroid cancer. Citation Format: Laura Pak, Aidana Rakhmankulova. Clinical and morphological characteristics as a predictors of the development of radioiodine resistance in thyroid cancer [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference on Molecular Targets and Cancer Therapeutics; 2025 Oct 22-26; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2025;24(10 Suppl):Abstract nr A144.