External Radiation Therapy for Papillary Carcinoma

Abstract

Surgical management and radioactive iodine ablation if required are the standard treatments for nonmetastatic papillary thyroid cancer. External beam radiation therapy (RT) to the neck has no role in the postsurgical management of most patients; however, a small group of patients with locally advanced disease will recur despite appropriate surgery and radioactive iodine. The characteristics of such patients, especially older patients with gross extrathyroid extension, will be discussed. The role of RT to control gross residual disease in the adjuvant setting following resection of gross tumor and for subsequent palliation will be described, as well as the effectiveness of RT in controlling gross disease that has not been resected. In patients with unresected disease, approximately 40 % of patients have a complete response of gross disease to RT and local control rates of about 60 % at 5 years. The evidence supporting adjuvant RT that comes mostly from single institutional studies that compare the local control following surgery and radioactive iodine with that of surgery, radioactive iodine, and RT will be reviewed, including our own data that showed in patients over the age of 60 with microscopic disease that RT resulted in a higher cause-specific survival (81.0 % and 64.6 % p = 0.04) and locoregional relapse-free rate (86.4 % and 65.7 % p = 0.01) compared to patients not given RT. The role of RT in treating metastases also will be briefly described. The technique of radiation and evidence supporting the use of intensity-modulated radiation therapy (IMRT) will be described as will the potential adverse effects or toxicity of radiation.