Multiple Factor Analysis On Achieving Disease-free Status By The First Radioactive Iodine Therapy On Post-operative Patients With Differentiated Thyroid Cancer

Background¹³¹I treatment is an important management method for patients with differentiated thyroid cancer.Unsuccessful ¹³¹I ablation drastically affects the prognosis of the patients.PurposeThis study aimed to analyze potential predictive factors influencing the achievement of a disease-free status following the first ¹³¹I therapy.Materials and methodThis retrospective review included 315 differentiated thyroid cancer patients,and multiple factors were analyzed.All included patients received total thyroidectomy by our specialized thyroid surgeons,and post-treatment whole body scan or diagnostic whole body scan were conducted after 6 to 7 months.Disease-free status was defined as no clinical or imaging evidence of tumor,stimulated Tg<1ng/m L with negative Tg Ab,and no uptake inside or outside the thyroid on the whole body scan 6 to 7 months after first ¹³¹I therapy.We assessed the following variables as possible influential factors for ¹³¹I ablation:age,gender,primary tumor size,pathological type,capsular invasion,pathological tumor stage,lymph node metastasis,distant metastasis,TNM stage,ATA risks,time interval between surgery and ¹³¹I therapy,pre-ablation Tg,and pre-ablation TSH.Analysis was performed using Statistic Package for Social Science?SPSS?version 17.0.ResultsA total of 315 DTC patients were recruited in our analysis.1.Between the unsuccessful and successful groups,age,gender,pathology,Capsular invasion American Joint Committee on Cancer tumor-node-metastasis staging system,time interval between surgery and ¹³¹ I therapy had no differences.The tumor size,pathological tumor stage,lymph node metastasis,distant metastasis,American Thyroid Association recommended risks,pre-ablation thyroglobulin?Tg?,and thyroid stimulating hormone?TSH?displayed significant differences between unsuccessful and successful group.2.Cutoff value of 3.525 ng/ml for pre-ablation Tg could be used to differentiate successful and unsuccessful outcome with a sensitivity of 77.12%,specificity of74.12%,PPV?positive predictive value?of 64.09%,and negative predictive value?NPV?of 84.39%.Cutoff value of 99.700?IU/ml for TSH could distinguish successful and unsuccessful ablation with a sensitivity of 57.63%,specificity of57.46%,PPV of 44.74%and NPV of 69.33%3.Binary logistic regression analysis showed that tumor stage T3 or T4,LN metastasis to N1b station,intermediate and high risks,pre-ablation Tg?3.525 ng/ml and TSH<99.700?IU/m L were significantly associated with unsuccessful outcomes.Logistic regression equation for achieving a disease-free status could be rendered as:y?successful treatment?=-0.270-0.503X₁?LN metastasis?-0.236 X₂?Tg?+0.015X₃?TSH?.This study demonstrated LN metastasis,pre-ablation Tg and TSH were the most powerful predictors for achieving a disease-free status by the first ¹³¹I therapy.ConclusionLN metastasis,pre-ablation Tg and TSH were the most powerful predictors for achieving a disease-free status by the first ¹³¹I therapy.Patients with LN metastasis,high pre-ablation Tg level and low pre-ablation TSH would be unlikely to achieve a disease-free status.