Papillary thyroid cancer with chest metastases only detected using radioactive iodine

Background: Insufficient information exists on the prognostic factors of papillary thyroid cancer (PTC) with chest metastases, which is detected only using a radioactive iodide (¹³¹I) whole body scan (WBS) but could not be detected using radiographic findings. The aim of this study was to analyze the clinical features and treatment results of patients with PTC. Methods: This retrospective study includes 17 patients diagnosed from 1985 through 2002. The clinical features and responses to treatment were compared between patients with diffuse lung metastases and those with focal lung or mediastinal metastases, and at the end of follow up the results were also compared between disease-free patients and those with persistent chest metastases. Results: The mean age of the 17 patients was 32.2±19.1 years. After a mean follow up of 89.6 ± 51.3 months, all 17 patients survived except for one who died of a non-thyroid-related disease. Six of the 17 patients were disease-free at the end of follow up, and eight of the 17 patients became free of chest metastases. The dose of ¹³¹I required to cure chest metastases was higher in the patients with diffuse lung uptake than those with focal chest uptake. The primary tumor size and serum thyroglobulin (Tg) level on the first finding of chest metastases differed markedly between disease-free patients and patients with persistent chest metastases. Conclusions: ¹³¹I scans can effectively demonstrate early chest metastases, which are difficult to detect from chest X-ray or computed tomography (CT). The prognosis for patients with papillary thyroid carcinoma with chest metastases detectable only using ¹³¹I is favorable. Additionally, the low serum Tg level on the first finding of chest metastases and the small size of the primary tumor may have favorable therapeutic outcomes.