External radiotherapy and radioiodine in the treatment of 359 thyroid cancers.

Between 1943 and 1965, 359 patients with carcinoma of the thyroid were treated by external radiotherapy or radioiodine out of a total number of 560 patients treated during the same period. In 65 of these patients surgery had been satisfactory from a macroscopic point of view. Prophylactic post-operative irradiation was given to 55 and the survival rate was 91 per cent at five years and 85 per cent at ten years. Ten received radioiodine, eight were alive at five years and six at ten years. In 95 patients excision of the tumour had been macroscopically incomplete. Fifty-four were treated by external radiotherapy and the survival rates were 50 per cent at five years and 48 per cent at ten years. For the differentiated carcinoma of this group 68 per cent were surviving at five years and 58 per cent at ten years. Of 41 patients treated with radioiodine, 75 per cent were surviving at five years and 31 per cent at ten years. Eighty-five patients were inoperable. Sixty were treated by external radiotherapy, the survival rates were 17 per cent at five years and 8.5 per cent at ten years. For the differentiated carcinomas of this group the survival rates were 24 per cent and 18 per cent. Twenty-five were treated with radioiodine, 26 per cent were surviving at five years and 4.5 per cent at ten years. The patients treated by external radiotherapy can be divided into two subgroups according to the technique of treatment and dose used. Between 1943 and 1955, patients were treated with conventional X rays (mean applied dose 2,800 rads), between 1956 and 1965 the patients were treated with 60Co (mean applied dose 5,000 rads). For the 45 patients of the first group, the survival rates were 35 per cent at five years and 32 per cent at ten years. For the 124 of the second group the respective survival rates were significantly higher: 60.6 per cent and 53 per cent. The results of external radiotherapy were similar to those of radioiodine at five years and better at ten years. In conclusion, a dose of 5,000 to 6,000 rads delivered by megavoltage external radiotherapy in five to six weeks, is well tolerated and effective mostly in differentiated carcinomas and medullary carcinomas. The survival rates of 64 patients whose metastases were unable to pick up iodine is practically zero at five years. For 68 patients with uptake in their metastases the survival rates were 53 per cent at five years and 23 per cent at ten years. The survival rate in patients with pulmonary metastases was higher than in patients with bony metastases (75 per cent versus 44 per cent at five years and 42 per cent versus 8 per cent at ten years.