Factors affecting disease-free status of differentiated thyroid carcinoma patients

The study aim was to assess factors that impact on the outcome of radioiodine therapy in patients diagnosed with differentiated thyroid carcinoma (DTC).

We performed a retrospective cohort study on 256 patients with DTC who underwent thyroidectomy and received radioiodine therapy during December 2003 to January 2012. All patients were followed up for at least 1 year. They were considered disease- free by the criteria of the revised American Thyroid Association Management Guideline for Patients with Thyroid nodules and DTC (ATA guideline 2009).

On Cox univariate analysis, factors associated with disease-free status were age<45, stage I tumor, low risk group by histopathology, unifocal tumor involvement, stimulated serum Tg level at 1st dose of radioiodine therapy and no distant metastasis from 1st post-treatment WBS (post RxWBS). On multivariate analysis, stage I tumor and stimulated serum Tg level at 1st dose of radioiodine therapy<30 ng/mL were the significant prognostic factors that increased disease-free rate by 1.73 times and 2.60 times, respectively (P-value<0.05).

Factors affecting the outcome of radioiodine therapy in our study were age, stage, risk of recurrence by histopathology, unifocal tumor involvement and 1st postRxWBS findings. From these factors, stage I tumor and stimulated serum Tg level at 1st dose of radioiodine therapy were independent prognostic factors that substantial increase the disease-free rate.