Clinical Efficacy of 125I Seed Implantation in the Treatment of Refractory Differentiated Thyroid Cancer

Data from RAIR-DTC patients hospitalized at Jiangxi Cancer Hospital from January 2015 to February 2022 were retrospectively collected.

In advance of the surgery, patients were informed about their condition, the expected efficacy of 125I seed implantation therapy, alternative treatments such as external beam radiotherapy and chemotherapy, as well as potential side effects and toxic effects. The preoperative evaluation process includes assessments of coagulation function, liver and kidney function, cardiopulmonary function, and local CT scans.

A collaborative effort between physicians and physicists was undertaken to establish a treatment regimen with a prescription dose ranging from 80 to 120 Gy. The patient accepted the treatment plan and signed an informed consent form. The CT-guided 125I seed implantation procedure was conducted according to the prescribed treatment regimen. Efficacy evaluations were conducted at pre-surgery, 1-, 3-, and 5-month post-surgery. The evaluations focused on lesion dimensions, serum thyroglobulin (Tg), TG antibodies (TGAb), thyroid-stimulating hormone (TSH) levels, pain levels, and adverse reactions.

Lesion size was determined using CT imaging. Lymph nodes were assessed based on their shortest diameter, while other target lesions were evaluated based on their longest diameter. Each measurable lesion underwent an average measurement derived from a minimum of three readings, with all measurements conducted by the same individual to minimize measurement discrepancies.

Response Evaluation Criteria in Solid Tumors (RECIST 1.1) [1] were used to assess treatment response. Use the Visual Analogue Scale to record patients' pain scores. Postoperative adverse reactions, including infection, bleeding, pneumothorax, bone marrow suppression, and seed displacement, were recorded. Radiation injury was graded according to the Radiation Therapy Oncology Group (RTOG) and European Organization for Research and Treatment of Cancer (EORTC) toxicity criteria [2].

The data were analyzed using IBM SPSS 26.0. The count data (n%) and skewed measures [Md (Q1, Q3)] are presented. Group comparisons were conducted using the paired Wilcoxon rank-sum test, with statistical significance set at P < 0.05.

This study was approved by the Ethics Committee of Jiangxi Provincial Cancer Hospital.

Inclusion criteria

Differentiated Thyroid Cancer (DTC) was confirmed by pathology, with local recurrence or distant metastasis of residual thyroid cancer and conforming to any of the following Iodine-Refractory Differentiated Thyroid Cancer (RAIR-DTC) criteria: (1) no uptake of 131I in the initial 131I treatment; (2) loss of iodine uptake capacity in previously functional iodine-avid lesions; (3) disease progression after 131I therapy, including gradual enlargement of the lesion and continuously increasing levels of serum thyroglobulin (Tg).

Exclusion criteria

Patients with severe physical diseases, such as severe dysfunction of the cardiac, pulmonary, hepatic, or renal systems, poor compliance, inability to tolerate 125I seed implantation, severe acute infectious or chronic infection with acute exacerbation, severe coagulopathy that may lead to serious complications like infection or bleeding, pregnant or lactating women affecting fetal and infant growth and development, patients with cachexia or expected survival of ≤3 Months and patients with positive serum anti-thyroglobulin antibodies (TgAb) that may impact the assessment of treatment efficacy.