MON-446 Anaplastic Thyroid Cancer Presenting with Brain Metastasis: 17-Year Progression Free Survival

Background: Anaplastic Thyroid Cancer is the most aggressive thyroid cancer with a median survival of just five months. Long term survival has been reported in locally aggressive cases, but has yet to be reported in metastatic disease. Case Information: A 34-year-old male presented with symptoms of dizziness, confusion, intermittent headaches, and erratic behavior for two weeks. CT of the head revealed a 1 cm ring enhancing lesion in the left parietal lobe with surrounding vasogenic edema. He was taken to the operating room for a left parietal craniotomy and a vascular, solid mass was removed. Initial pathology suggested papillary thyroid origin due to positive staining for thyroid transcription factor (TTF) and thyroglobulin (Tg). On exam, he had a palpable 3 cm mass in the right thyroid lobe with no associated adenopathy. He underwent thyroidectomy to optimize post-operative radioactive iodine treatment. Intraoperative frozen section revealed anaplastic thyroid cancer and final pathology revealed anaplastic carcinoma identical to the brain lesion. The tumor pathology showed extension through the thyroid capsule with lymphovascular invasion and one of two positive lymph nodes. Post-operatively, he underwent 15 cycles of whole brain radiation therapy for a total of 35 Gy. Two additional brain lesions were identified after thyroidectomy and a third was identified after whole brain radiation. He underwent stereotactic radiosurgery of these three lesions less than two months after thyroidectomy. The patient went on to receive modified mantle field irradiation (46 cycles, total 55.2 Gy) to the neck, thyroid bed, and the upper mediastinum. Additionally, he received chemotherapy with doxorubicin 6-8 weeks and temozolomide for 2 years. Thyroid uptake studies showed minimal residual iodine-avid disease and, in the setting of chemotherapy-induced cytopenias, radioactive iodine treatment was not administered. The patient has currently survived 17 years post-treatment. His persistent, but stable, brain lesions are being followed with serial imaging. He remains clinically and neurologically asymptomatic. Conclusions: This is the first case presenting with long-term survival in a patient with metastatic anaplastic thyroid carcinoma. A multidisciplinary course with early aggressive surgical removal, adjuvant treatment with chemotherapy and radiation, and long term imaging follow up may be an acceptable treatment plan for stable patients. References: Smallridge RC, Ain KB, Asa SL, Bible KC, Brierley JD, Burman KD, et al. American Thyroid Association guidelines for management of patients with anaplastic thyroid cancer. Thyroid. 2012;22(11):1104-39.