Thyroid cancer treatment:Long-term effects and new developments

Thyroid cancer is increasingly common. This is especially the case for differentiated thyroid cancer (DTC), which has a favorable prognosis. Treatment consists of surgical removal of the thyroid gland, radioiodine treatment, and life-long administration of relatively high doses of thyroid hormone. This treatment is effective, but also rather aggressive since it can result in the occurrence of both short- and long-term adverse effects. There used to be little attention for this issue, as cancer-related outcome was less favorable. Nowadays, we see a lot of DTC patients with small tumors who have a near-normal life expectancy. For these patients long-term adverse effects of treatment are very important since they can negatively impact quality of life. In this thesis we therefore studied the occurrence of long-term effects of DTC treatment. We found that atrial fibrillation (a cardiac rhythm disturbance) and mortality due to cardiovascular diseases are more common in DTC patients as compared to the general population. Furthermore, we found that a part of patients have salivary glands dysfunction following radioiodine treatment. Fortunately, the adverse effects of this treatment on bone marrow function were limited. Furthermore, there is a small group of thyroid cancer patients with more aggressive disease. For these patients, cure is often not achievable. Therefore, we studied the efficacy and toxicity of tyrosine kinase inhibitors (a new class of drugs) that have been studied in these patients. In addition, we studied the hereditary material of several thyroid cancers in an attempt to understand more of thyroid cancer pathogenesis