Up-to-date program of treatment and long-term follow-up of the patients with differentiated thyroid carcinoma

Full text: Primary treatment for thyroid carcinoma depends on the process dissemination and disease prognosis. The former includes 1) surgery, which is the first and chief method of treatment almost in all cases; 2) I-131 natrium iodide treatment following surgery to achieve ablasticity of the residual tumor tissue, which is especially in some cases; 4) inhibiting hormone therapy is important, if unfavorable prognostic factors are present; 3) distant radiation therapy is possible. The criteria for determining the volume of surgery are the size, morphology, character and rate of growth of the tumor, presence of regional metastases and their mobility, age of the patient, signs of invasion to the adjacent organs. From oncology perspective, minimum volume of intervention in tumors > 2 cm is extrafascial hemistrumectomy, when the tumor is located in the lateral portions; extrafascial hemistrumectomy with removal of the isthmus and resection of the adjacent 1/3 of the neighboring tumor tissue, when the tumor is located in the center and medial portions of the lobe or in the isthmus. Thyroidectomy is a method of choice in large tumors. This allows avoiding development of bilateral cancer, local relapses as well as improving survival and reducing the death rate. Thyroidectomy facilitates I-131 treatment and increases sensitivity of radionuclide body scan with the use of I-131. Diagnostic determining of thyroglobulin for revealing the tumor metastases is possible only after thyroidectomy. Treatment with I-131 sodium iodide is the second essential stage of multimodality treatment for thyroid carcinoma. Multifocal differentiated cancer is found in 20-30% of the patients; residual thyroid tissue, the source of thyroglobulin, reduces informativity of the tumor marker determining; the residual thyroid tissue, as a rule, competes with the relapses and metastases of thyroid cancer for I-131 absorption; hidden distant metastases of thyroid carcinoma can be revealed by I-131 scan only on complete ablation of the residual thyroid tissue. All these prove for I-131 treatment with the purpose of ablation of the residual tumor tissue. In the post-operative period, I-131 treatment is indicated in case of non-radical surgery, or when the radical charter of the surgery is doubtful. The advantages of this approach have been demonstrated by the reduction in the incidence of relapses and increase of the life span. According to the international experience and the standard treatment protocols for differentiated thyroid cancer, planned distant gamma-therapy (DGT) is considered unexpedient due to low sensitivity of the tumor tissue. DGT can be indicated in case of incomplete or doubtful surgery, especially in elderly patients with poorly differentiated tumor, in case, when the tumor is poorly differentiated and I-131 absorption is inconsiderable or completely absent. In case when surgery is not possible due to the tumor process dissemination, DGT can stabilize the tumor growth. On the other hand, DGT is not indicated in case of radical surgery or in children, even with an extended tumor process. In this case, the protocol of treatment includes surgery followed by I-131 therapy. External irradiation should not be performed, if a pronounced therapeutic effect is not expected. In other words, gamma-therapy is advisable only when surgery and I-131 treatment have proven to be ineffective. The purpose of a long-term follow-up is revealing locoregional relapses and distant metastases. The patient examination is based on combined use of clinical examination, echography of the neck region, thyroglobulin (Tg) level assessment in the blood serum, whole body scan with residual activities using I-131 natrium iodide. Increased Tg level is considered to be the only sign of thyroid cancer metastases in the operated patients, even when the findings of clinical, x-ray and scintigraphic studies are negative. Comparison of sensitivity of diagnostic scintigraphy with I-131, sonography of the neck and assessment of Tg level in the operated patients after radioiodine ablation of the residual thyroid tissue suggests that laboratory study of Tg level correlates with the clinical state of the patients and the findings of isotopic techniques in 99.5% of the patients. During dynamic observation it is necessary to control TSH level for adequate hormone therapy with the purpose of inhibiting thyrotropin secretion to prevent relapses and metastases of the thyroid tumor. (author)