Thyroid Cancer

Thyroid cancer is not a common neoplasm although the incidence is rising in the USA.

The most common pathology is papillary and follicular and in general, the prognosis is excellent. Most cases are treated with surgery followed by radioiodine ablation.  The incidence of recurrence and metastases is ~10% in low risk patients (young with small tumors) and ~ 25% in high risk patients (older with large tumors).  For a long time, recurrence was treated with repeated courses of radioiodine and if recurrence occured post 1 131 treatment no other options were available. Chemotherapy was notoriously not effective for the differentiated thyroid cancers.

Currently, three therapeutic options are available (not FDA approved but recommended by NCCN guidelines) that were studied in Phase II or III trials. Sorafenib (FDA approved for renal and hepatocellular carcinoma) is a multi targeted kinase inhibitor shown to have a high response rate in thyroid cancer. It is a pill with the most common side effects being rash and diarrhea.  Sunitinib is also a multikinase inhibitor (FDA approved for renal cell cancer and GIST) it is also a pill with minimal side effects. Axitinib a selective inhibitor OR VEGFR 1-2-3 also an oral agent showed a response rate of ~30%. Major side effects hypertension, diarrhea, nausea and anorexia.

Most recently pazopanib, another oral agent htat has antiangiogenic properties by targeting VEGFR 1-2-3 as well as PDGFR and CKIT (FDA approved for renal cell carcinoma) has also shown a high response rate in thyroid cancer. Side effects include hypertension, EKG changes, bleeding and diarrhea.

Most of these drugs are fairly well tolerated and can stabilize a patients disease for a prolonged period of time. Increase knowledge of mutations associated with thyroid cancer furnish targets for new therapeutic options.