[Diagnosis and treatment of differentiated thyroid carcinoma].

Thyroid cancer is the most common endocrine malignancy. More than 90% of primary thyroid cancers are differentiated papillary or follicular types. The prognosis for patients with differentiated thyroid carcinomas is favorable. Female gender and younger age (<50 years) are good prognostic factors. The diagnosis of papillary thyroid cancer is not difficult with ultrasonography and fine-needle aspiration cytology under ultrasonography, whereas that of follicular cancer is difficult, especially of minimally invasive follicular carcinoma. The diagnosis of most follicular cancer is made by pathologic diagnosis postoperatively. The primary treatment of differentiated thyroid carcinoma is thyroid surgery with lymph node dissection. The extent of resection of the thyroid gland depends on size the of the thyroid cancer and area of invasion. If a patient has distant metastasis, total thyroideectomy and radioactive iodine ablation therapy, followed by L-thyroxine therapy, should be offered. The extent of initial surgery, indications for radioiodine ablation therapy, and the degree of thyroid-stimulating hormone (TSH) suppression are all issues that are still being debated. The aim of TSH-suppressive therapy is to restore euthyroidism and to decrease serum TSH levels to reduce the growth and progression of thyroid cancer.