Rare renal metastases from differentiated thyroid carcinoma: early clinical detection and treatment based on radioiodine.

OBJECTIVE

The aim of this study was to explore the clinical characteristics of renal metastatic cancer, the methods for its detection by radioiodine (131)I, and the response to (131)I treatment in fourteen patients with renal metastases from differentiated thyroid carcinoma (DTC).

SUBJECTS AND METHODS

DTC patients (n = 2,955) that received treatment with (131)I were retrospectively analyzed. Scans ((131)I-WBS, (31)I-SPECT/CT and/or (18)F-FDG-PET/CT) were performed after an oral therapeutic dose of (131)I. Therapeutic efficacy was evaluated based on changes in Tg and anatomical imaging changes at renal lesions.

RESULTS

Among these 14 patients, 11 had avidity for (131)I, but three patients did not accumulate (131)I after (131)I treatment. In the 11 (131)I-positive renal lesions, 10 cases were detected by (131)I-SPECT/CT combined with another imaging modality and one case by (131)I-WBS combined with ultrasonography (US). In the three (131)I-negative renal lesions, two cases were detected by 18F-FDG-PET/CT and one case by computed tomography (CT). In 11 patients with (131)I-avid renal metastases, Serum Tg levels in 81.82% (9/11) patients showed a gradual decline, and 18.18% (2/11) of the patients showed a significant elevation. There was no marked difference in serum Tg before the last (131)I treatment (Z = 0.157; p = 0.875). Only one patient presented partial response, eight patients exhibited stable disease, and renal metastases progressed in two patients showing progressive disease. No patients reached complete response.

CONCLUSION

(131)I-SPECT/CT, combined with another imaging modality after (131)I-WBS, can contribute to the early detection of renal metastases of DTC. (131)I therapy is a feasible and effective treatment for most DTC renal metastases with avidity for (131)I.