Evaluation of CYFRA 21.1 as a dedifferentiation marker of advanced thyroid cancer

Abstract

Purpose of the Study:Well-differentiated thyroid carcinomas have good prognosis, but as it de-differentiates, the survival rates go down. Early identification of such patients needs a marker which indicates the dedifferentiation process. CYFRA 21.1 has also shown to be increased in patients with 131I refractory thyroid cancer. We tested whether CYFRA 21.1 can differentiate between 131I avid and refractory tumors.Methodology:Well-differentiated thyroid cancer patients with known distant metastases were accrued and tested for stimulated and unstimulated thyroglobulin and CYFRA 21.1. All patients underwent 131I whole-body scan, 131I post therapy scan, and 18F-Fluorodeoxyglucose positron emission tomography-computed tomography. Those with even a single 131I nonavid lesion were considered 131I refractory disease. CYFRA 21.1 of both 131I avid and nonavid was compared, and CYFRA 21.1 levels against disease extent were analyzed.Results:CYFRA 21.1 levels were significantly elevated in 131I refractory group. A cutoff value of 2.07 ng/ml distinguished between 131I avid and refractory disease with high sensitivity and specificity (88% and 89. 7%, respectively). However, CYFRA 21.1 levels were similar in patients when analyzed based on disease sites.Conclusion:CYFRA 21.1 can be utilized to differentiate between 131I avid and refractory diseases. Further long-term studies are required to use it as a predictive and prognostic marker.