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[Incidental differentiated thyroid carcinoma is less prevalent in Graves' disease than in multinodular goiter]

OBJECTIVE

Risk factors for differentiated thyroid carcinoma (DTC) are poorly understood, but serum TSH levels, thyroid nodularity, and presence of autoimmunity are well-recognized factors that modulate DTC prevalence. TSH stimulates proliferation of both normal and neoplastic follicular cells. Consequently, thyroid-stimulating immunoglobulins (TSI), because of its TSH-like action, should induce DTC progression in patients with Graves' disease (GD). The study objective was to compare the prevalence of incidental DTC in patients undergoing thyroidectomy for benign thyroid disease.

METHODS

The pathology reports of 372 patients with preoperative diagnosis of euthyroid multinodular goiter (EMG) or hyperthyroidism were reviewed. Scintigraphy results and serum TSI levels were used to diagnosed either GD or hyperactive MG (HMG) to hyperthyroid subjects. Prevalence of DTC in each category was calculated using a Chi-square test.

RESULTS

EMG, GD, and HMG were diagnosed in 221, 125, and 26 patients. There were 58 DTCs, distributed as follows [n (%)]: EMG, 49 (22.2%); GD, 8 (6.4%), and HMG, 1 (3.8%). Difference in prevalence of incidental DTC between the groups was statistically significant (p<0.001). After adjustment for age, patients with EMG had a greater DTC prevalence than GD patients, with an OR of 4.17 (p<0.001). Tumor size (mm, mean ± SD) was 6.92 ± 11.26, 1.97 ± 1.85, and 9.0 for EMG, GD and HMG respectively (p=0.017).

CONCLUSIONS

Incidental DTC was less prevalent in GD as compared to EMG irrespective of age. This finding may suggest a predisposition to develop DTC in patients with thyroid nodular disease and/or a potential effect of autoimmunity to protect against development of neoplastic disease.

[Differentiated thyroid carcinoma: survival and prognostic factors]

BACKGROUND AND AIMS

Differentiated thyroid carcinoma (DTC) is the most common endocrine tumor. DTC has a good prognosis and survival rates higher than 85%. The aim of our study was to assess our current survival rate and to analyze prognostic factors.

PATIENTS AND METHODS

A retrospective analysis was conducted of 308 patients with DTC (93.5% with papillary tumors, 78.8% women). Mean age at diagnosis was 45.4±15.8years, and mean follow-up time was 8.9±6.8years. The whole group was treated and followed up using the same protocol at our hospital. The following data were collected: age at diagnosis, sex, histology, TNM stage, treatments, and date and cause of death. Survival probability was calculated using Kaplan-Meier analyses. Prognostic factors were analyzed using a univariate log rank test and a multivariate Cox regression analysis model.

RESULTS

Twenty-six patients died during follow-up, 15 of them (4.9%) from DTC. Thyroid carcinoma-related survival was 92.7% for the whole group. In multivariate analyses, the following parameters were associated to a significantly increased risk of death from DTC: presence of distant metastases, follicular histology, age at diagnosis older than 60years, and extrathyroid invasion.

DISCUSSION

Our survival rate is similar to that reported in literature. Assessment of prognostic factors related to an increased risk of death in our patient group, is essential to establish active therapeutic approaches in high risk patients.

[Potential risks of the adverse effects of thyrotropin suppression in differentiated thyroid carcinoma]

In patients with differentiated thyroid carcinoma, long-term inhibition of thyrotropin (TSH) secretion through levothyroxine administration is required when there is evidence of persistent or recurrent disease. In these cases, levothyroxine doses should be monitored to achieve the objectives of inhibiting TSH and avoiding clinical hyperthyroidism. The possibility that suppressive therapy may produce deleterious effects is still controversial, mainly in elderly patients. There are many studies on the potential harmful effects of suppressive therapy on various organs and systems with discrepant results. However, there is no scientific evidence that the clinical impact of these effects is significant.