Medullary thyroid cancer outcomes in patients with undetectable versus normalized postoperative calcitonin levels.

Calcitonin (Ct) is a sensitive diagnostic biomarker and one of the most important prognostic factors for medullary thyroid cancer outcomes; however, the significance of postoperative Ct levels remains controversial. This study evaluated the differences between normal and undetectable postoperative Ct levels in patients who had undergone surgical treatment for medullary thyroid cancer. Patients who experienced postoperative Ct level normalization had a higher risk of disease recurrence than those with undetectable Ct levels after surgery.