Predicting Structural Progression-Free Survival After Surgery for Medullary Thyroid Carcinoma.

INTRODUCTION: Medullary thyroid cancer (MTC) is an aggressive tumor for which surgery is the only curative treatment. However, after surgery, some patients may experience persistence/recurrence. It is important to identify the prognostic factors that may affect structural disease-free survival (SDFS), which may influence the follow-up of our patients. OBJECTIVE: To assess SDFS in patients with MTC and related factors. METHODS: A retrospective observational study was conducted in a tertiary hospital including patients with MTC without distant metastases. The following variables were assessed: sex, age, heritability, type of surgery, calcitonin (Ct) and CEA, tumor size, stage, lymph nodes ratio (LNR), vascular invasion, high risk, structural disease, and SDFS. A descriptive and comparative univariate and multivariate analysis of SDFS was performed using SPSS version.29 and Cox regression, defining structural disease as the event. p < 0.05 was considered statistically significant. RESULTS: A total of 140 patients with a median age of 34 years were evaluated. Forty-six percent (n = 65) were male. Twenty-two percent (n = 31) had sporadic MTC, 75% (n = 106) had MEN2a, and 2% (n = 3) had MEN2b. The median calcitonin level was 182.5pg/mL and median follow-up was 179.5 months. Structural disease occurred in 24% of patients (n = 33). The variables that influenced the SDFS were as follows: sporadic CMT, older age, preoperative CEA, size, lymph node involvement, higher LNR, vascular invasion and high risk, and Ct levels > 150pg/mL at 6-12 months. In the multivariate analysis, age, LNR, T category, and postoperative Ct remained independent predictors. CONCLUSION: The SDFS in MTC is significantly influenced by LNR, T category, and postoperative Ct levels at 6-12 months.