Management of Anaplastic Carcinoma

Abstract

An excellent recent review of anaplastic carcinoma includes a brief overview of management of this highly aggressive tumor with external radiation therapy (1). Anaplastic carcinoma is the least radiosensitive of the thyroid neoplasms. The giant cell variety shows little response to external irradiation, while the small-cell variant is more radiosensitive (2). Megavoltage external radiation may be utilized after needle aspiration or simple biopsy to establish the diagnosis. Surgical excision is recommended to remove or debulk as much of the neoplasm as is possible. However, it is extremely difficult for the surgeon to leave a thyroid area completely free of this tumor. In one series of 43 patients with distant metastases, it was noted that only one had virtually all of the tumor removed at the original thyroidectomy (3). Maximal control of any local disease in the neck by a combination of extensive surgery followed by external radiation is critical to survival. A tracheostomy may be necessary before starting the external irradiation to provide an adequate airway during therapy, although tracheostomy may be associated with poor local wound healing, which can lead to postponement of the radiotherapy (4). Unfortunately even with 6500 to 6000 cGy to the primary lesion, the neck and the superior mediastinum, control of the tumor is almost never accomplished, and some series of patients have indicated no increase in survival, even in the face of apparently initial good responses to radiation therapy (5). However, some very slight survival benefit may be gained by treatment, with 3000 cGy or more being associated with 6 months survival in one series (6),whereas survival only averaged 2 months after lower doses. Because of the marked dedifferentiation of these tumors, they do not trap radioiodine, and as a result ¹³¹I has not generally been used to treat anaplastic carcinoma.