RADIATION THERAPY IN THE CONTROL OF PERSISTENT THYROID CANCER

Abstract

Between 1935 and 1964, 58 patients received external radiation therapy for local control of thyroid cancer. In each instance the residual cancer tissue was not resected because thyroid cartilage, trachea, or hypopharynx was invaded. In 33 patients the extrathyroidal extension was grossly evident. In the other 25, there was persumed microscopic involvement of 1 or more of these structures. Patients in whom the extrathyroidal disease was limited to resectable structures, such as the strap muscles or cervical lymph nodes, are not included in the study. 1. Regardless of whether radiation therapy permanently controls a papillary carcinoma of the thyroid, it usually produces a favorable and often long-lasting response. Of the 9 patients given radiation therapy at least 5 years ago for grossly evident papillary carcinoma, 5 have survived 5, 6, 10, 14, and 25 years without recurrence, 1 is living with recurrence at 5 years, and the other 3 have died of recurrence at periods between 5 and 18 years after treatment. All 12 patients with probable microscopic persistent papillary cancer have been observed at least 5 years and 6 have been observed for more than 10 years; none has shown evidence of local recurrence to date. 2. In patients with follicular carcinoma, the long periods of control of several tumors suggest that some do respond to local radiation therapy even though control is less reliable than in the papillary carcinomas. Of the 8 patients with follicular carcinoma treated at least 5 years ago, 6 are without local recurrence. Three of 7 observed 10 years or more are without recurrence at 10, 16, and 18 years after treatment. For patients with locally persistent follicular carcinoma and no evidence of distant spread, local radiation therapy should be attempted before resorting to systemic therapy with radioiodine. 3. Three of the 7 patients with anaplastic carcinoma obtained some benefit from radiation treatment. One was without local recurrence for 6 years, then died of distant metastases. A second patient has been free of disease for 2 years and in a third recurrence developed only after 3 years. 4. All 5 patients with giant cell carcinoma were dead within 2 months. 5. Of 6 patients with lymphosarcoma initially limited to the thyroid, 3 were observed without evidence of the lymphoma locally or elsewhere for periods of 3, 17, and 20 years.