Medullary thyroid cancer--current treatment strategy, novel therapies and perspectives for the future

Medullary thyroid cancer (MTC), an uncommon and slow-growing tumor, is difficult to eradicate when metastasis or recurrence develops. This review describes therapeutic approaches to patients with recurrent sporadic MTC, management of advanced cases of MTC, and future treatment options. A literature review of treatment of MTC in humans was conducted. Surgery is currently the only potentially curative treatment for MTC; complete tumor resection and removal of suspicious nodes is the most important initial treatment to prevent recurrence and metastasis. When recurrence or metastatic MTC develops, the decision for continued observation or initiation of systemic therapy is based on the degree of tumor aggressiveness. Lymph node involvement, calcitonin doubling time, types of RET mutation, and tumor stage are factors that help determine the need for further treatment. Therapeutic options for aggressive and inoperable MTC primarily include tyrosine kinase inhibitors, external beam radiation therapy, or other medications. Among tyrosine kinase inhibitors, vandetanib is the first drug that is FDA approved for treatment of MTC. Focused external beam radiation therapy can be reconsidered for patients with cervical node involvement. Although other targeted drug therapies have been tried, definitive clinical studies are lacking. In recurrent or advanced MTC, when systemic therapy is warranted, vandetanib is available for use in treatment; however, side effects of this drug can be problematic, and impact on overall survival is presently unknown. Newer therapeutics are being studied with the goal of balancing control of tumor growth with maintaining the patient's quality of life.