Quantitative assessment of preoperative risk factors for aggressive course of medullary thyroid carcinoma

Objectives: to study the long-term results of surgical treatment of patients with medullary thyroid carcinoma and evaluate the significance of prognostic factors. Materials and methods: the continuous retrospective study included 169 patients with histologically confirmed medullary cancer who were initially operated at the Northwestern Center for Endocrinology and Endocrine Surgery of the SPbSU University Clinic from 2010 to 2016. They were divided into prognostic groups according to the level and dynamics of postoperative calcitonin and clinical manifestations of the disease. Results: The study allowed to assess the effect of predictive factors on the risks of progression and recurrence in medullary thyroid cancer. Size of the primary tumor more than 2 cm significantly increases the risk of disease progression (OR=6,56 (0.52-17.96) p=0,00001495). Invasion of the thyroid capsule and metastases to regional lymph nodes are even more important prognostic value as OR=49,08 (10.72-224.89), p=0,00000011 и OR=30,63 (9,75-96,27), p<0.0000001 respectively. Regional MTC metastases are a significant threat to the life of the patient. This fact is a fundamental difference with differentiated thyroid carcinoma were regional metastases do not affect the prognosis. This study failed to link the prognosis to the patient's age. As expected the level of basal calcitonin >600 pg/ml affects the prognosis (OR=6,65 (2,53-17,59) p=0.01055). Its prognostic value is comparable to the size of the primary tumor and significantly less than the presence of regional and distant metastases. Conclusions: Unfavorable prognosis in 21 (12.4%) observed patients is associated not only with the presence of distant metastases, but also and independently with regional ones.