Local and Systemic Treatment of Unresectable Disease

Abstract

Papillary thyroid cancer is the most common subtype of thyroid cancer. Although incidence of the disease is increasing, survival rates are excellent, with 10-year survival around 90%. However, approximately 15–30% of patients with papillary thyroid cancer are found to have metastases (half of them at initial presentation), most commonly seen in the lungs (50%), bones (25%), both lungs and bones (20%), or occasionally in other sites (5%). Many of these patients can be treated, but complete remission is only seen in one third (J Clin Endocrinol Metab 91(8):2892–9, 2006). When progression is seen after initial treatment with thyroidectomy and radioactive iodine, other options remain. Surgical resection of locoregional disease (in selected patients) generally offers the best chance of cure; however, reoperation is generally riskier than initial surgery due to scar tissue formation. If resection is not an option due to the extent of disease, involvement of critical structures, or patient refusal, radioactive iodine treatment is generally recommended. However, advanced disease is frequently refractory to therapy with radioiodine; studies are underway of several therapies that may resensitize tumor to iodine. External beam radiotherapy (EBRT) may be employed to treat either locoregional recurrence or distant metastatic disease. TSH suppression remains an important part of therapy. Lastly, therapy with tyrosine kinase inhibitors (TKIs), either approved by the Food and Drug Administration [FDA] or as part of a clinical trial, may be recommended in symptomatic patients with progressive metastatic disease (Thyroid 26(1):1–133, 2016).