Long-Term Outcome of 444 Patients with Distant Metastases from Papillary and Follicular Thyroid Carcinoma: Benefits and Limits of Radioiodine Therapy

TLDR

The study aimed to estimate the cumulative (131)I activity required to treat distant metastases in 444 patients with papillary or follicular thyroid carcinoma. Patients received 3.7 GBq (100 mCi) (131)I every 3–9 months for two years, then annually, with thyroid hormone withdrawal and suppressive doses between courses, until all uptake disappeared or a cumulative 22 GBq was reached. Negative imaging was achieved in 43 % of patients, most after 3.7–22 GBq, with 96 % of negatives occurring after this dose range, nearly half appeared after five years, only 7 % recurred, and 10‑year survival was 92 % for negative versus 19 % for non‑negative patients.

Abstract

The goal of this study was to estimate the cumulative activity of (131)I to be administered to patients with distant metastases from thyroid carcinoma.A total of 444 patients were treated from 1953-1994 for distant metastases from papillary and follicular thyroid carcinoma: 223 had lung metastases only, 115 had bone metastases only, 82 had both lung and bone metastases, and 24 had metastases at other sites. Treatment consisted of the administration of 3.7 GBq (100 mCi) (131)I after withdrawal of thyroid hormone treatment, every 3-9 months during the first 2 yr and then once a year until the disappearance of any metastatic uptake. Thyroxine treatment was given at suppressive doses between (131)I treatment courses.Negative imaging studies (negative total body (131)I scans and conventional radiographs) were attained in 43% of the 295 patients with (131)I uptake; more frequently in those who were younger, had well-differentiated tumors, and had a limited extent of disease. Most negative studies (96%) were obtained after the administration of 3.7-22 GBq (100-600 mCi). Almost half of negative studies were obtained more than 5 yr after the initiation of the treatment of metastases. Among patients who achieved a negative study, only 7% experienced a subsequent tumor recurrence. Overall survival at 10 yr after initiation of (131)I treatment was 92% in patients who achieved a negative study and 19% in those who did not.(131)I treatment is highly effective in younger patients with (131)I uptake and with small metastases. They should be treated until the disappearance of any uptake or until a cumulative activity of 22 GBq has been administered. In the other patients, other treatment modalities should be used when tumor progression has been documented.