Background: Recent decades have seen a rise in the incidence of well-differentiated (mainly papillary) thyroid carcinoma around the world. In Germany, the age-adjusted incidence of well-differentiated thyroid carcinoma in 2010 was 3.5 per 100 000 men and 8.7 per 100 000 women per year.
Methods: This review is based on randomized, controlled trials and multicenter trials on the treatment of well-differentiated thyroid carcinoma that were retrieved by a selective literature search, as well as on three updated guidelines issued in the past two years.
Results: The recommended extent of surgical resection depends on whether the tumor is classified as low-risk or high-risk, so that papillary microcarcinomas, which carry a highly favorable prognosis, will not be overtreated. More than 90% of localized, well-differentiated thyroid carcinomas can be cured with a combination of surgery and radioactive iodine therapy. Radioactive iodine therapy is also effective in the treatment of well-differentiated thyroid carcinomas with distant metastases, yielding a 10-year survival rate of 90%, as long as there is good iodine uptake and the tumor goes into remission after treatment; otherwise, the 10-year survival rate is only 10%. In the past two years, better treatment options have become available for radioactive-iodine-resistant thyroid carcinoma. Phase 3 studies of two different tyrosine kinase inhibitors have shown that either one can markedly prolong progression-free survival, but not overall survival. Their more common clinically significant side effects are hand-foot syndrome, hypertension, diarrhea, proteinuria, and weight loss.
Conclusion: Slow tumor growth, good resectability, and susceptibility to radioactive iodine therapy lend a favorable prognosis to most cases of well-differentiated thyroid carcinoma. The treatment should be risk-adjusted and interdisciplinary, in accordance with the current treatment guidelines. Even metastatic thyroid carcinoma has a favorable prognosis as long as there is good iodine uptake. The newly available medical treatment options for radioactive-iodine-resistant disease need to be further studied.