BACKGROUND
Medullary thyroid cancer is a rare type of thyroid cancer that can run in families. Medullary thyroid cancer arises from the C-cells of the thyroid. The C-cells secrete the hormone calcitonin. Importantly, the C-cells do not take up iodine. In contrast, the most common type of thyroid cancer, papillary thyroid cancer, arises from the thyroid follicular cells which take up iodine to make thyroid hormones. Because of this, papillary thyroid cancer can be treated with radioactive iodine to destroy the cancer cells. Radioactive iodine does not work to treat medullary thyroid cancer.

The main treatment for medullary thyroid cancer is surgery to remove the cancer. Finding medullary thyroid cancer early is important because treatment (mainly surgery) works best before the cancer spreads. However medullary thyroid cancer can be hard to find early. Ultrasound findings are often nonspecific, and thyroid biopsy misses medullary thyroid cancer in up to half of cases. This leads to delayed diagnosis and misses opportunities for curative surgery. Measuring levels of calcitonin, the hormone that C-cells make, can help, but results in the middle range are often unclear and may worry patients unnecessarily. Because of these problems, researchers wanted to find a better and more reliable way to use blood tests to detect medullary thyroid cancer early.

The goal of this study was to see if using calcitonin along with procalcitonin (a hormone that becomes calcitonin) together could improve the accuracy of diagnosing medullary thyroid cancer.

THE FULL ARTICLE TITLE
Schonebaum LE, et al. Progastrin-releasing peptide and procalcitonin as additional markers in the diagnostic workup for medullary thyroid carcinoma. Thyroid 2025;35(9):1030-1038; doi: 10.1089/thy.2024.0293. PMID: 40576708.

SUMMARY OF THE STUDY
Researchers studied adults who had thyroid nodules and were being evaluated for possible thyroid cancer. The study included patients from hospitals in Europe between 2006-2025. First, doctors measured calcitonin levels in the blood. If calcitonin levels were slightly high, they then measured another procalcitonin levels. The researchers compared these test results with the patients’ final diagnoses to see how accurate the tests were.

The study found that when calcitonin levels were only mildly high, procalcitonin helped clearly tell who had medullary thyroid cancer and who did not. Using calcitonin first and then procalcitonin correctly identified all patients with medullary thyroid cancer and correctly ruled out cancer in almost all patients who did not have it. This approach worked very well and reduced false alarms.

WHAT ARE THE IMPLICATIONS OF THIS STUDY?
Using calcitonin first and adding procalcitonin when needed is a very accurate way to check for medullary thyroid cancer. This approach may help patients avoid unnecessary surgery, extra tests, and anxiety when calcitonin levels are only slightly elevated. At the same time, it helps doctors find medullary thyroid cancer earlier, when treatment is most effective.

— Maria Brito, MD, ECNU

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