Pulmonary metastasis of differentiated thyroid carcinoma: treatment results in 101 patients

Well differentiated thyroid carcinoma was diagnosed in 1,127 patients at The University of Texas M.D. Anderson Hospital and Tumor Institute at Houston from 1951 to 1981. Of those 1,127 patients, 101 had documented pulmonary metastasis. A retrospective analysis was conducted, and these patients were followed up until 1983. The primary tumors in these patients were histologically classified as papillary (67%), follicular (22%), or Hurthle cell (11%). The age at diagnosis ranged from 5-87 yr. Lung metastasis was diagnosed by both chest x-ray and positive uptake of 131I in 49 patients. Forty-two patients had positive chest x-ray results and negative 131I scans, and 10 patients had positive 131I scans and negative chest x-ray results. The patients were treated with radioactive iodine (76%), chemotherapy (9%), external radiotherapy (2%), or supportive care only (14%). Sixty-seven patients subsequently died of thyroid carcinoma. Our studies showed the following. 1) Patients who were younger than 40 yr of age at diagnosis had better prognosis (71% survival) compared with those over 40 yr of age (16% survival; P less than 0.01). 2) Uptake of radioactive iodine by lung metastasis is a favorable prognostic factor, especially in patients with negative radiological findings. Patients treated with radioactive iodine have a longer survival than those not treated with radioactive iodine (P less than 0.002). 3) The incidence of pulmonary metastasis is significantly less in patients who are treated by total thyroidectomy than in those treated with less than total thyroidectomy (P less than 0.03). 4) The incidence of pulmonary metastasis is lowest in patients with papillary carcinoma (9%), compared with that in patients with follicular (13%) or Hurthle cell (25%) carcinoma.