Background/Objectives: The presence of distant metastases is the main cause of death in medullary thyroid carcinoma (MTC). However, due to the rarity of this cancer, few studies have thoroughly analyzed the variables influencing the development of distant metastases. The objective of this study was to evaluate, in patients with MTC, the factors associated with the occurrence of synchronous and metachronous distant metastases. Methods: An analytical, observational, retrospective cohort study was conducted at a tertiary hospital. Patients with histologically confirmed MTC, both sporadic and familial (MEN2 syndrome), were included. The influence of epidemiological variables, heredity, complementary tests, surgical factors, histological features, staging, and disease progression was assessed. A univariate comparative analysis was first performed, followed by a multivariate analysis using logistic regression. Results: This study included 146 patients, of whom 75% (n = 109) had familial MTC. Lymph node involvement at diagnosis was observed in 36% (n = 52). During follow-up, distant metastases developed in 14% (n = 21) of patients, including five cases present at the time of diagnosis. The median follow-up was 214 months (IQR 106–289). The presence of distant metastases was associated with an increased risk of mortality. Factors associated with distant metastases included age, calcitonin level, hereditary status, lymph node involvement, and overall stage. In multivariate analysis, the lymph node ratio (LNR) remained the only significant predictor (OR 29.124). Conclusions: Several variables were related to the presence of distant metastases. Among them, the LNR emerged as the independent predictor of both synchronous and metachronous distant metastases.

Introduction. In medullary thyroid carcinoma (MTC), calcitonin levels and TNM staging are established prognostic factors. However, the diagnostic accuracy of cytology in MTC is poor. In this context, microRNAs (miRNAs) may be useful as valuable biomarkers, although evidence in MTC remains scarce. The aim of this study was to determine the expression of several miRNAs in patients with MTC and to investigate their association with clinical aggressiveness. Methods. Twenty-five patients undergoing surgery for MTC were included. miRNA expression profiles (miR-183-5p, miR-375-5p, miR-144-3p, miR-34a-5p, and miR-200c-3p) were analyzed in both histological samples of MTC and paired healthy thyroid tissue. cDNA synthesis was performed using the miRCURY LNA RT Kit (Exiqon Ref. 339340 Qiagen, Hilden, Germany). Gene expression was studied by real-time PCR using the QuantStudio 5 kit (Applied Biosystem). Variables included epidemiological, clinical, and follow-up variables. Statistical analysis: SPSS v.29. Kruskal–Wallis, Mann–Whitney U, and Spearman’s ρ tests were used. Results. Sixty percent (n = 15) were female and 56% (n = 14) had familial CMT. The mean age at diagnosis was 41.8 years. The median expression of miR-200c-3p, miR-144-3p, miR-34a-5p, miR183-5p, and miR-375-5p was 1.02, 0.923, 1.002, 7.666, and 2.226, respectively. Significant differences in expression were found for miR183-5p and 375-5p (p = 0.001) compared to paired healthy thyroid tissue. Patients with a higher disease-free survival (DFS) showed higher expression of 200c-3p (ρ = 0.456, p = 0.022). Conclusions. The expression of miRNAs 183-5p and 375-5p may help us to diagnose MTC, and a lower expression of miRNA 200C-3p may indicate a higher clinical aggressiveness.

Background: Pheochromocytoma (PHEO) is a rare neuroendocrine tumour with a strong genetic link, which therefore may modify its clinical behaviour and prognosis. The aim of the study is to evaluate the epidemiological and clinical differences between patients with sporadic and familial PHEO, as well as the specific differences in the index cases. Methods: A retrospective analysis of 136 patients in a tertiary hospital (1984–2021). Epidemiological, clinical, and histological variables were analysed. Statistics: SPSS 28.0 software was used. Univariate and multivariate logistic regression analyses were performed. p < 0.05 was considered statistically significant. Results: 64.71% of the cases (n = 88) presented a genetic mutation (familial cases). Additionally, 32.39% (n = 23) corresponded to index cases and the rest to screening cases. The main differences between patients with familial and sporadic PHEO were age (OR = 0.93 (0.89–0.97)), blood pressure-related symptoms (OR = 0.22 (0.06–0.89)), bilaterality (OR = 15.49 (3.76–63.84)), and size (OR = 0.70 (0.54–0.92)). Among patients with sporadic PHEO and index cases, only bilaterality was significant (OR = 13.53 (1.24–144.34)). Conclusions: Patients with familial PHEO diagnosed by screening differ from sporadic cases in terms of age, clinical features, and size. However, patients with sporadic PHEO only differ from index cases by a lower presence of bilaterality, which reaffirms the importance of genetic screening of patients with PHEO and their relatives.