| Thyroid carcinoma is rare among human malignancies (about 1.5%), but is the most frequent endocrine cancer. Some investigations suggest that the incidence of thyroid carcinoma is rapidly increasing recent years. Most of the thyroid carcinoma are low malignant and have an optimal prognosis usually. Early diagnosis and suitable management in time are important to increase the survival rate.By reviewing a lot of references, especially recent 5 years, the author made a summary of thyroid carcinoma in this article from etiological factor, clinical classification, pathologic features, diagnosis and therapy. Radioiodine therapy for thyroid cancer has been discussed in detail including the destruction of residual thyroid tissue and metastasis treatment.The risk factors of thyroid carcinoma are not very definite. Long-term clinical researches and epidemiological investigations indicate that some factors have a relation with thyroid cancer, including effects of radiation and hormone, intake of iodine, etc. Some oncogenes and anti-oncogenes participate the development process of thyroid carcinoma, e.g. oncogene of RET/PTC, TRK, RAS and anti-oncogene p53. Cytokine also plays a role in this process and vascular endothelial growth factor (VEGF) is the most important. Penetrating cognition of the mechanism may provide new clue or pathway to management of thyroid carcinoma.The origin of the papillary, follicular and anaplastic thyroid carcinoma is follicular epithelium, while medullary thyroid carcinoma is ultimobranchial cells (C cell). The papillary and follicular thyroid carcinoma, together termed differentiated thyroid carcinoma (DTC), comprise the majority of thyroid cancers and have an optimal prognosis. Anaplastic thyroid carcinoma is rare but highly malignant, its five-year survival rate is the lowest of all thyroid carcinoma. Medullary thyroid carcinoma includes both sporadic MTC and family MTC. Because of the secreting of calcitonin, 5- hydroxytryptamine, prostaglandin and so on, patients can have some clinical manifestation such as diarrhea, dizziness or cardiopalmus.There is no specific diagnosis method for thyroid carcinoma, serum Tg is a useful tumor marker during the post-surgical follow-up of thyroid carcinoma. Thyroid ultrasonography, CT and MRI play an important role in evaluation of thyroid nodules. The results of fine-needle aspiration (FNA) cytology can determine the nature of a thyroid nodule with certainty.Surgery is the primary treatment for all papillary and follicular thyroid cancers. The objective is to remove all tumor foci. The type of surgical intervention depends on the patient's age and the location, size or histological type of the nodule. Most clinicians recommend near-total or total thyroidectomy.Radioiodine131 management of postsurgical thyroid carcinoma includes ablation of residual thyroid tissue and metastasis treatment.The use of 131I is based on the following assumptions: ablation of residual normal thyroid tissue facilitates the early detection of recurrence based on serum Tg measurement and 131I whole body scan (WBS) ; elevates sensitive of post-therapy WBS and may reveal previously undiagnosed tumors; may decrease the recurrence rate and possibly the mortality rate.The indications for ablation therapy with 131I after surgery for thyroid carcinoma are: incomplete tumor resection; a high risk of mortality/recurrence; distant metastases. If patient's general condition is well, WBC>3.0×109, and do not during pregnancy or lactation, this treatment can be carried out. A low-iodine diet or drug should be advised before 131I administration; thyroid hormone treatment is withdrawn for 4-6 weeks; some conventional examination such as hepatic function, Thyroid ultrasonography, ECG are necessary. The optimal dose of ablation therapy with 131I is controversial, most of the specialist recommend a dose ranging from 2.8GBq (75mci) to 5.5GBq (150mci), depending on the clinician's choice. Whole body scan is performed 5 to 7 days after 131I treatment. This can be important in those cases where there were previously negative investigations in the presence of higher serum Tg levels.The metastasis of thyroid carcinoma can be lymph node, lung, bone or soft tissue. Most of the clinicians agree with a dose from 3.7GBq (100mci) to 7.4GBq (200mci), depending on the concrete location. The majority should receive at least thrice treatments and the interval time usually is 4-6 months.The therapeutic efficacy of 131I is related to a lot of factors, including the patient's age; course of disease; the location, size and histological type of the metastasis. The key issues rely on the early detection of metastases and management in time.All patients affected by thyroid carcinoma should be treated with thyroid hormone after thyroidectomy and 131I management. Such therapy has a dual objective: to correct hypothyroidism and to suppress stimulated growth of persistent or recurrent neoplastic disease by reducing TSH. The correct dose will lead to low or undetectable serum TSH values and serum FT3 concentrations within the normal range.The aim of follow-up is to evaluate the suitability of the thyroxine therapy and to detect persistent or recurrent thyroid carcinoma. Serum Tg is the most sensitive and specific marker of DTC. Tg should not be detectable, whereas an increased serum concentration of Tg is associated with metastatic or recurrent of thyroid carcinoma. WBS with 131I is a technique usually complementary to Tg evaluation. Patients receive a dose of 74 to 185 MBq (2 to 5 mci) of 131I, and scanning is performed 2 to 3 days after 131I administration.The author concludes that 131I therapy is effective at extending survival time, both as a sole therapeutic modality and as an adjunct to surgery. Radioisotope therapy can be recommended for cases in current management. Objective: To treat residual thyroid tissue and metastasis in postoperative patients with thyroid cancer by 131I .Methods: DTC patients with no metastasis after surgery received oral 131I treatment with total doses of 60-300 mci, 60-150mci per time; with functionality metastasis, received accumulated doses of 600mci, 120-200mci each time. Two treatment at least intervals 2 months Results: 17 of 20 cases with no metastasis had successful ablation of residual thyroid tissue after the first administration of 131I, 3 cases after the second treatment and all I scanning is negative in recheck. 15 cases with bone or lung metastasis give complete remission after 3 courses of treatment, no abnormal scanning is detected after 3 or 5 years, blood Tg are always negative. One case of undifferentiated thyroid cancer, thyroid disappear but mediastinum metastasis have been not changed during 3 months treatment of 131I. Conclusions: 131I can remove residual thyroid tissue of different pathologic types of DTC after surgery, it also can diagnose , treatment and prevent recurrence of well-differentiated metastasis.
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