Treatment Outcomes of External Beam Radiation Therapy for Unresectable Locally Advanced Thyroid Cancer with or without Metastasis: A Retrospective Single-Center Study

Abstract

We evaluated treatment outcomes of external beam radiation therapy (EBRT) for unresectable locally advanced thyroid cancer (LATC) with or without metastasis. We enrolled 11 LATC patients who underwent EBRT (median age: 76 (45–83) years; six males and five females). Eastern Cooperative Oncology Group performance statuses of 0 (n = 3), 1 (n = 1), 2 (n = 6), and 3 (n = 1) were observed. Histologic types included papillary carcinoma (n = 5), anaplastic carcinoma (n = 3), and squamous cell carcinoma (n = 3). The organs invaded by the tumor that caused it to be deemed unresectable were common carotid artery (n = 5), trachea (n = 4), aorta (n = 1) and larynx (n = 1). The median follow-up time was 6 months. One, seven, two, and one patient showed complete response (CR), partial response (PR), stable disease, and progressive disease, respectively. The rate of local CR+PR was 73%; moreover, 75% of patients achieved a >30% tumor size reduction within 6 months. The median local progression-free survival of patients with local CR+PR was 11.5 (4–68) months. The median overall survival was 6 (1–68) months. Grade 3 acute complications occurred in five (45%) patients. No patients had Grade 4 or 5 complications. In conclusion, EBRT reduced the tumor volume in 75% of LATC patients without inducing severe toxicity. This therapy should be considered as a treatment option for LATC.

Keywords

• external beam radiation therapy
• locally advanced thyroid cancer
• tyrosine kinase inhibitor
• squamous cell thyroid cancer