Low thyroglobulin level and successful ablation can predict the disease free status in patients with differentiated thyroid cancer

Objectives The aim of this study is to investigate the predicting factors for the disease free status in patient with differentiated thyroid cancer.

Methods Eighty five patients with differentiated thyroid cancer (female; 68, mean age 44 ± 12, papillary; 83, follicular; 2) were retrospectively reviewed between November 2001 and December 2008. All patients underwent total thyroidectomy and I-131 ablative therapy (IAT) (3.7 – 5.4 GBq). The success or failure of ablation were assessed 6-9 months after the IAT with the reference of undetectable thyroglobulin (Tg) and negative I-131 whole body scan (WBS). Afterward, the decision for persistent disease was evaluated once more using TSH stimulation (follow up period after 1^st IAT; 13 to 84 months, median 58 months, criteria of persistent disease: more than 10ng/ml TSH-stimulated Tg and/or positive WBS). Clinical and tumoral factors such as sex, age, pathologic type, Tg at IAT (Tg1), Tg after IAT (Tg2), the size of tumor mass, lymph node involvement, AJCC stage, ablation status and I-131 WBS uptake pattern were considered for multivariate analysis.

Results Fourteen patients of 85 patients remained persistent disease (16.5%). Tg1, Tg2, and ablation status were associated with disease status on univariate analysis. From the multivariate analyses, Tg1 was the only independent predictor for disease free status (odds ratio=1.0125; 95% confidential interval=1.003-1.0221; p=0.01).

Conclusions Tg1 is the only independent predictor for disease free status in patients with differentiated thyroid cancer.