Evaluation of CYFRA 21.1 as a Dedifferentiation Marker of Advanced Thyroid Cancer

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.

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.

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.

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.