Long-Term Follow-Up of Patients With Differentiated Thyroid Cancer Who had Negative 131I Whole-Body Scan at First Evaluation After Treatment

Abstract

The evaluation of patients with differentiated thyroid cancer is commonly based on serum thyroglobulin (Tg) measurement and 131I whole-body scan (WBS). The first follow-up (6-12 months after initial treatment) shows the response to therapy, a prognostic factor.The aims of the study were to describe the clinical outcome during a long-term follow-up of patients with negative 131I WBS in the first evaluation, and to assess clinical and histological characteristics related to the outcome in this patient population. This retrospective study reviewed data from 209 patients followed at 2 Brazilian hospitals. A minimum of 10 years of follow-up was required. During mean follow-up of 13.7 ± 4.2 years, 20% of patients developed recurrence. At the end of follow-up, 21% of patients had persistent disease. The clinical and histological characteristics related to adverse outcomes (recurrence or persistent disease) were lymph node metastases at diagnosis, high risk according to American Thyroid Association (ATA) classification, and incomplete response to treatment. Stimulated Tg levels (under thyroid hormone withdrawal) and basal Tg levels (with thyroid hormone) greater than 10 ng/mL at first evaluation were associated with an adverse outcome. Negative WBS at first evaluation should not be used as an isolated prognostic factor. This must be considered together with histopathological (ATA classification, lymph node metastases) and clinical/laboratory characteristics (stimulated and basal Tg; response to therapy).