Radioiodine treatment of metastatic thyroid carcinoma: the Royal Marsden Hospital experience.

The case records of 235 patients who were treated for differentiated thyroid cancer between 1949 and 1981 were reviewed. Forty-two (18%) had distant metastatic spread outside the neck and received radioiodine (131I) therapy. In cases where the distant spread was confined to the lungs, 54% of patients were alive, free of disease, 10 years after 131I treatment was started. By contrast, no patient with skeletal involvement has survived for 10 years and only one for five years after treatment. A variety of cytotoxic drugs has been tried on an ad hoc basis with no notable success. One patient developed preleukaemia three months after completion of 131I treatment, but no other serious side effects were observed. Factors that influence the behaviour of metastatic thyroid carcinoma are discussed and a possible revised approach to 131I therapy is suggested in the light of these findings.