Implications of mediastinal uptake of I-131 with regard to surgery in patients with differentiated thyroid carcinoma

BACKGROUND. Findings of mediastinal uptake of I-131 after surgical treatment for differentiated thyroid carcinoma (DTC) are common, especially in young patients. Given the frequency of false-positive findings, a protocol for diagnostic and their- apeutic strategies would be useful. With the goal of accurately selecting management strategies, the authors analyzed their data and data found elsewhere in the literature for correlations with the incidence of mediastinal I-131 uptake and with treatment for patients exhibiting such I-131 uptake. METHODS. All patients with DTC who were treated between 1978 and 2000 at Groningen University Hospital (Groningen. The Netherlands) and who received adjuvant I-131 ablation therapy were included in the current analysis, which involved retrospective review of all relevant data. RESULTS. Five hundred four patients with DTC initially underwent total thyroidectomy, with additional I-131 ablation performed for 489 of these patients. In 48 of 489 patients (9.8%), I-131 uptake was seen in the mediastinum on a posttreatment scan. Analysis of those 48 patients and of cases in the literature demonstrated that serum thyroglobulin levels, risk status, and the presence of thymus on radiologic images were important in the surgical decision-making process. CONCLUSIONS. Mediastinal uptake of I-131 on posttreatment scans was found in approximately 10% of patients after total thyroidectomy for DTC. Based on the current data and the data presented in the literature, the authors developed a flow chart for determining appropriate treatment strategies, which included mediastinal dissection for high-risk patients and for patients with serum thyroglobulin levels > 10 ng/mL. (C) 2004 American Cancer Society