Abstract: The authors report a case of anaplastic thyroid carcinoma which was treated with chemotherapy and radiotherapy and proved to achieve pathological CR (complete response) after a radical operation. A 53-year-old female presented with a mass of about 4cm in diameter arising from the left lobe of her thyroid and surrounding her cervical esophagus. Pre-operative aspiration cytology and open biopsy revealed the tumor was a giant cell anaplastic carcinoma. There was no sign of distant metastasis. Two cycles of chemotherapy were very effective in treating the tumor but regrowth appeared to occur during hyperfractionated radiotherapy. A radical operation, including a resection of the larynx, cervical trachea and esophagus, was successfully performed and no living cancer cells, only granul…