Regarding anaplastic carcinoma, which of the following statement is true?

ATC is the most aggressive form of thyroid carcinoma with a disease-specific moality approaching 100%. A typical manifestation is an older patient with dysphagia, cervical tenderness, and a painful, rapidly enlarging neck mass. Patients frequently have a history of prior or coexistent DTC, and up to 50% have a history of goitre. Findings may also include superior vena cava syndrome. The clinical situation deteriorates rapidly into the tracheal obstruction and rapid local invasion of surrounding structures.p53 mutations are found in 15% of tumoursIt is 100% fatal if initially, it is operable thyroidectomy done. Postoperative external-beam irradiation or adjunctive chemotherapy adds little to the overall prognosis but should be consideredRef: Sabiston 20e, page no: 933