The Effect of131I Therapy on Survival of Patients with Metastatic Papillary or Follicular Thyroid Carcinoma

Abstract

A standardized dosimetry procedure was used to select patients for radioiodine therapy from a group of 46 patients with remote metastases from papillary or follicular thyroid cancer, studied over a 10-year period. Eight patients under the age of 40 with papillary cancer were all treatable by dosimetry criteria; metastases regressed in all instances after therapy, and one patient died of thyroid carcinoma. Of 17 older patients (over age 40) with papillary carcinoma only 8 were treatable, and 1 responded to therapy. Six of 8 older patients treated for papillary carcinoma died, as did 5 of 9 untreated patients. The survival time for ¹³¹I-treated older patients was not significantly different from that of untreated patients. Eleven of 18 older patients with follicular carcinoma retained sufficient ¹³¹I to warrant therapy and 6 demonstrated tumor regression after therapy. The survival time of treated patients was significantly enhanced by radioiodine therapy as compared to that of untreated patients. Three young patients with follicular carcinoma were also studied. The data are compatible with the following conclusions: Metastatic papillary cancer in patients under the age of 40 is quite responsive to ¹³¹I therapy and the prognosis in this age group is good. Metastatic papillary cancer is a lethal disease in patients over the age of 40 and only about half of the patients retain sufficient radioiodine in metastases to warrant therapy. The response to therapy in this group is poor and therapy does not apparently influence survival. Older patients with follicular carcinoma are more treatable than are patients of a similar age with papillary carcinoma. About one third of patients with follicular carcinoma respond to radioiodine therapy and the survival time of treated patients is significantly enhanced over that of untreated patients.