Clinical Characteristics of Patients With Renal Cell Carcinoma and Metastasis to the Thyroid Gland.

Introduction: Renal cell carcinoma (RCC) is the most common malignancy to metastasize to the thyroid gland. The aims of this study are as follows: (1) to analyze the clinical characteristics of patients with thyroid involvement of RCC and (2) in patients with RCC thyroid metastasis, to determine whether RCC metastasis to glandular organs only portends a better prognosis compared with other patterns of RCC metastasis.

Methods: Patients from Wake Forest Baptist Medical Center (WFBMC) diagnosed with thyroid metastasis from RCC were identified and medical records retrospectively examined. A systematic review of the literature for cases of RCC involving the thyroid gland was also performed. The clinical characteristics of the institutional cohort and the cases from the literature review were compared. Descriptive statistical analysis was performed, and overall survival (OS) was summarized using Kaplan-Meier methods.

Results: The median OS for the WFBMC cohort was 56.4 months. In the literature review cohort, OS of patients with RCC thyroid metastasis was 213.6 months, and there was no statistically significant survival difference based on the site of metastasis. Median survival after thyroid metastasis from RCC for the WFBMC and literature cohort was 21.6 and 45.6 months, respectively.

Conclusions: Metastatic RCC should be included in the differential of a new thyroid mass. Treatment directed at the thyroid metastasis results in prolonged survival in some cases. Further analysis into the genomic differences and mechanisms of thyroid metastasis is warranted.