Endocrine Abstracts

Introduction and objectives: Papillary Thyroid Carcinoma (PTC) accounts for 84% of all thyroid cancers and has shown increasing incidence in recent decades. The greater availability of imaging studies and fine needle cytology partly explains this phenomenon. However, the rising incidence of advanced-stage thyroid carcinomas suggests that this trend may be partially due to a change in the biological behaviour of these tumours. In recent years, evidence has grown indicating that diabetes mellitus (DM) may increase the risk of thyroid neoplasms, with this increased risk estimated at 25% in a prospective cohort study with a 10-year follow-up. The mechanisms involved in this increased risk remain uncertain, with several studies pointing to genetic factors, altered TSH secretion, lesions secondary to oxidative stress, hyperinsulinism, changes in adipokine secretion, and increased secretion of pro-inflammatory factors. This study aims to analyze the impact of diabetes mellitus on the molecular profile of PTC.

Methods: A sample of 45 patients with PTC who underwent thyroidectomy between 2014 and 2015 and screened for mutations in the BRAF, RAS, and pTERT genes was characterized for the prevalence of DM, thyroid function, BMI, lipid profile, and cardiovascular comorbidities at the time of PTC diagnosis. Insulin resistance was estimated by calculating the Glucose-Triglyceride Index (GTI).

Results: At diagnosis of PTC, the sample composed of 40 women and 5 men, presented an average age of 55 (±14.4) years; 22% of the patients were diagnosed with diabetes; 51% with arterial hypertension; 49% with dyslipidemia; 16% with hypothyroidism. The average BMI was 29.3 (±5.3) kg.m^-2, with 32% overweight, 41% obese, and 16% fulfilling the WHO 1999 criteria for metabolic syndrome. Insulin resistance was considered when GTI > 4.68 and was present in 36% of the sample. Additionally, patients with DM presented a higher prevalence of metabolic syndrome (60%) and insulin resistance (60%; average GTI 4.72 ± 0.40). The molecular profile of PTC revealed that the most mutated gene was BRAF (64%), and although not statistically significant, the prevalence of BRAFV600E was higher in the patients with DM (OR 2,667 [0.492; 14.461], P 0.256).

Conclusion: Despite the limitations of this study, such as its retrospective nature and the small sample size, there appears to be a positive association between the prevalence of DM and the BRAF^V600 mutation. The next step will involve increasing the sample size to validate the findings of this study.