Reduced insulin sensitivity in differentiated thyroid cancer patients with suppressed TSH.

OBJECTIVE: TSH-suppression is a therapy for thyroid cancer management, but it may lead to adverse effects, which should be balanced with its benefits. Previous studies evaluating the consequences of TSH suppression on insulin sensitivity have only been done with indirect techniques, and results were controversial. Therefore, we aimed to assess insulin sensitivity in patients with thyroid cancer and suppressed thyroid-stimulating hormone (TSH) with the most appropriate direct method (hyperinsulinemic-euglycemic clamp) in order to get a more conclusive response about the topic. METHODS: A group of 20 non-obese and non-diabetic thyroid cancer patients with suppressed TSH underwent a hyperinsulinemic-euglycemic clamp to evaluate insulin sensitivity. Their results were compared to the results of a sex and body mass index (BMI) -paired control group composed of 20 healthy volunteers. RESULTS: Patients were all female, aged 36.8 ± 10.2 years-old, with mean TSH 0.1 ± 0.1 µIU/mL and mean BMI 26.2 ± 3.3 kg/m2. Insulin sensitivity, determined by the insulin-stimulated glucose uptake (M-value), was lower in the patients group (4.2 ± 1.6 mg/min*kg versus 5.8 ± 1.7, age-adjusted p-value = 0.0205). CONCLUSION: This study shows for the first time that subclinical thyrotoxicosis in patients with thyroid cancer is associated with insulin resistance, as measured by hyperinsulinemic-euglycemic clamp technique. Such finding may be taken into consideration by clinicians when balancing risks and benefits of TSH-suppression therapy in thyroid cancer patients.

Factors related to mortality in patients with papillary and follicular thyroid cancer in long-term follow-up.

PURPOSE: Differentiated thyroid cancer (DTC) includes papillary thyroid cancer (PTC) and follicular thyroid cancer (FTC). They have different biological behavior but are frequently analyzed together in studies. We aimed to identify factors associated with mortality in those two different cancer subtypes. METHODS: Case series study, with clinical-pathological analysis of the characteristics of 424 patients with PTC and 89 patients with FTC, correlating them to survival rates in a single institution. RESULTS: Patients were followed from 1983 to 2011. Mean follow-up time was 9.4 years for FTC (range 1-36.6 years) and 6.8 years for PTC (range 1.1-30.7 years). Mean age at diagnosis was 51.2 ± 15.5 for FTC and 41 ± 14.7 years for PTC. 50.62% of FTC nodules sized 1.1-4 cm and 20% of PTC sized ≤1 cm. Cox multiple regression analysis evidenced distant metastasis at diagnosis (p = 0.0038; relative risk (RR) 41.247, 95% confidence interval (CI) 3.317-512.986), lymph node metastasis at diagnosis (p = 0.0081; RR 50.98, 95% CI 2.783-934.026) and vascular/lymphatic invasion (p = 0.0039; RR 40.424, 95% CI 3.287-497.177) as factors related to mortality in FTC patients. For PTC, the factors were distant metastasis at diagnosis (p < 0.0001; RR 32.5, 95% CI 6.676-158.543) and degree of differentiation (poor versus well differentiated, p = 0.003; RR 10.4, 95% CI 2.218-49.487). CONCLUSION: The common factor that influenced mortality for FTC and PTC patients was distant metastasis at diagnosis, increasing mortality rate by 41 times in FTC and 30 times in PTC patients. The different factors influencing mortality for different DTC types highlight the importance of analyzing them separately.