Calcitonin level in the blood of patients with medullar thyroid cancer: association with carcinoma characteristics

The literature data on the existence of a relationship between the level of calcitonin (CT) and the presence and localization of metastases of medullary thyroid carcinoma (MTC) in the lymph nodes of the neck are ambiguous. While discussions about the diagnostic value of determining the level of CT focus on clarifying the range of its concentration increase 021in its concentration in the presence of metastases of different localization, the significance of other aggressive characteristics of MTC has received limited attention. However, such information may be useful for the prediction of recurrence or residual metastatic disease. Objective — to determine the possible relationship between the aggressive characteristics of MTC and the level of CT in the patients’ serum with medullary cancer. Materials and methods. A retrospective analysis of data from 82 patients with MTC who were examined and operated on between 2000 and 2024 was conducted. We analyzed the level of CT in the blood serum before and after surgery, tumor size, localization of metastases in the lymph nodes of the neck, the presence of multifocality, invasiveness and association of MTC with chronic autoimmune thyroiditis, as well as the number of patients who were diagnosed with incomplete biochemical remission after surgical treatment. Results. The existence of a clear correlation between the size of the MTC and the level of CT in the serum of patients has been confirmed, which decreases for the residual CT content after thyroidectomy. The increase in the level of CT in the blood of patients with metastases in the central or lateral lymph nodes of the neck is significant, but does not differ from each other, and with extensive metastasis it is even less than with the localization of metastases separately in the central or lateral compartments. An association has been established between the characteristics of MTC and an increase in the level of CT in the blood serum of patients: the highest concentration of CT is observed in the case of multifocal carcinomas and tumors with extrathyroidal invasion, and the lowest in patients with non‑invasive carcinomas. Incomplete biochemical remission was most often observed in the presence of metastases and in MTC with extrathyroidal invasion. Conclusions. The combination of different clinico‑oncological and morphological characteristics of MTC is responsible for the varying degrees of elevation of CT levels in the blood of patients with medullary cancer. The frequency of incomplete biochemical remission in patients after surgical treatment does not depend on the localization of metastases in the lymph nodes of the neck and is minimal for tumors up to 20 mm in size and non‑invasive; it was most often observed in the case of MTC with extrathyroidal invasion.