Procalcitonin levels predict clinical course and progression-free survival in patients with medullary thyroid cancer

BACKGROUND: Procalcitonin has been well established as an important marker of sepsis and systemic infection. The authors evaluated the diagnostic and predictive value of calcitonin and its prohormone procalcitonin in medullary thyroid cancer. METHODS: The authors systematically explored the ability of calcitonin and procalcitonin to identify medullary thyroid cancer and predict the endpoints local recurrence and distant metastases, as well as the progression-free survival. Patients with C-cell hyperplasia; patients after thyroidectomy for differentiated thyroid cancer, goiter, or Graves disease; and healthy subjects served as controls. The study was performed in accordance with the Reporting Recommendations for Tumor Marker Prognostic Studies of the National Cancer Institute. RESULTS: Sixty-nine medullary thyroid cancer patients and 96 controls were included (median observed interval: 10.9 years [range, 1.4-47.5 years]; 981.8 patient-years). The 1-year, 5-year, 10-year, and 20-year recurrence rates were 9%, 34%, 45%, and 56%, respectively. Calcitonin had a higher diagnostic accuracy for detecting medullary thyroid cancer than procalcitonin (area under the curve [AUC], 0.94; 95% confidence interval [95% CI], 0.90-0.99 vs AUC, 0.89; 95% CI, 0.83-0.95 [P = .038]). The procalcitonin:calcitonin ratio predicted disease progression (AUC, 0.63; 95% CI, 0.51-0.75 [P = .036]) and progression-free survival (hazards ratio, 1.49; 95% CI, 1.09-2.04 [P = .013]). CONCLUSIONS: The results of the current study indicate a superior diagnostic accuracy of calcitonin and an independent predictive value of the procalcitonin:calcitonin ratio. These findings may lead to improved diagnostic and therapeutic strategies for medullary thyroid cancer patients.