Biomarker-based risk stratification for previously untreated medullary thyroid cancer.

Preoperative neck ultrasonography may yield false-negative findings in more than one-third of medullary thyroid cancer (MTC) patients. If not cleared promptly, cervical lymph node metastases may emerge subsequently. Reoperations entail an excess risk of surgical morbidity and may be avoidable. This comprehensive investigation aimed to evaluate in a head-to-head comparison the clinical utility of pretherapeutic biomarker serum levels (basal calcitonin; stimulated calcitonin; carcinoembryonic antigen) for indicating extent of disease and providing biochemical stratification of pretherapeutic MTC risk. This was a retrospective analysis. The setting was a tertiary referral center. Included were 300 consecutive patients with previously untreated MTC. The intervention was compartment-oriented surgery. Stratified biomarker levels were correlated with histopathologic extent of disease. Higher biomarker levels reflected larger primary tumors and more lymph node metastases. Stratified basal calcitonin serum levels correlated better (r = 0.59) with the number of lymph node metastases than carcinoembryonic antigen (r = 0.47) or pentagastrin-stimulated calcitonin (r = 0.40) levels. Lymph node metastases were present in the ipsilateral central and lateral neck, contralateral central neck, contralateral lateral neck, and upper mediastinum, respectively, beyond basal calcitonin thresholds of 20, 50, 200, and 500 pg/ml. Bilateral compartment-oriented neck surgery achieved biochemical cure in at least half the patients with pretherapeutic basal calcitonin levels of 1,000 pg/ml or less but not in patients with levels greater than 10,000 pg/ml. Most newly diagnosed MTC patients, i.e. those with pretherapeutic basal calcitonin levels greater than 200 pg/ml, may need bilateral compartment-oriented neck surgery to reduce the number of reoperations.