[Therapeutic approach of differentiated and nondifferentiated cancer of the thyroid]

Outcome after treatment for differentiated thyroid carcinoma is good: 10-year survival rate is 80%. The surgical procedures should however be adapted to prognostic factors of the carcinoma and limited to selected cases with good prognosis in order to prevent unwarranted postoperative sequellae in cases of highly advanced disease. The most important prognostic factor is local extension. Rate of recurrence increases 4-to 6-fold in case of local invasion. The diameter of the tumor (under or over 4 centimeters) and the degree of vascular invasion are also very important in determining prognosis. The independent role of lymph node invasion is debated. Total thyroidectomy is the indicated surgical procedure; the rate of postoperative complications is about 4%. Systematic node dissection is not indicated but should be reserved for cases with poor prognosis. Picking nodes is recommended in cases with good prognostic factors. Radiotherapy should always be performed in case of poor prognosis but its efficacy is not as good as surgical resection of residual tumoral tissue. Hormonal therapy should also be adapted to prognostic factors. Follow-up is based on clinical, ultrasonographic and scintigraphic findings. Outcome after treatment for undifferentiated thyroid carcinoma is poor. Surgery, radiotherapy and chemotherapy must be associated. Surgery is performed before or after chemotherapy depending on the degree of local invasion.