Analysis Of Common Factors Influencing The ¹³¹I Therapeutic Efficacy For Differentiated Thyroid Cancer

Objective: The aim of this study is to investigate the risk factors influencing the 131I therapeutic efficacy and prognosis for differentiated thyroid cancer (DTC) patients by analyzing retrospectively their clinical and pathological features and preoperative thyroid hormone level.Methods: 337 cases with differentiated thyroid cancer ready to receive 131I therapy who had complete postoperative pathological results and preoperative thyroid hormone level were selected from department of Nuclear Medicine, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology during the period of 1995 to 2010. Group was divided according to the range of normal thyroid hormone level and TNM stage. All data was analyzed based on the thyroid globulin (Tg) level under stimulated by thyroid stimulating hormone (TSH) after treated with 131I, thyroglobulin antibody (TgAb) level, and outcome of 131I-whole body scan (131I-WBS) to evaluate therapeutic efficacy.Results: The therapeutic efficacy was influenced by preoperative free triiodothyronine (FT3) level, there was significantly better effect in patients with preoperative FT3 level above 3.1 pmol/L than those below the level (P=0.005); But if the boundary level was 6.8 pmol/L, there was no statistical difference (P=0.412). Different preoperative free thyroxine (FT4) (P=0.069) and TSH levels (P = 0.668) had no effect on the therapy, and so age (P=0.065) and the presence of envelope involvement or not (P=0.166) also had not. Therapeutic efficacy for female patients was significantly superior to male patients (P=0.000). When local soft tissue was involved, therapeutic efficacy was bad than those no local involvement (P=0.013). Maximum diameter of the tumor greatly influenced the therapeutic efficacy (P=0.001), therapeutic efficacy was significantly better in patients that maximum diameter of tumor was less than 1cm (P=0.000) and 1~2cm (P=0.003) than those tumor diameter was 2~4cm, but there was no statistical difference between less than 1cm and 1~2cm (P=0.323). Therapeutic efficacy in patients without lymph node metastasis was significantly better than those with lymph node metastasis (P=0.000), and was greatly related to the lymph node number (P=0.000). The patients comorbid benign thyroid disease had a better therapeutic efficacy than those without other thyroid disease (P=0.000), and different types of benign thyroid disease also could influence it (P=0.010). Therapeutic efficacy in patients with chronic lymphocytic thyroiditis was superior to other benign thyroid diseases (P=0.002).Conclusion: 1. There was a better therapeutic efficacy for those patients who were women, Preoperative FT3 level was not less than 3.1pmol / L, local soft tissue were not involved, tumor size was not more than 2cm, no lymph node metastasis, and comorbid benign thyroid disease.2. Preoperative FT4 and TSH levels, patient age, and simple envelope involvement had no influence on the therapy.