Follow-up regimen of differentiated thyroid carcinoma in thyroidectomized patients after thyroid hormone withdrawal

J Nucl Med. 2000 Apr;41(4):643-6.

Abstract

For differentiated, nonmedullary thyroid carcinoma, postsurgical ablation of thyroid remnants and treatment of residual tumor and metastases with 131I is a potentially curative therapy. The aim of this study was to optimize the diagnostic protocol for the follow-up of thyroidectomized patients.

Methods: Two hundred fifty-four patients (187 females, 67 males; mean age, 45 y; range, 8-83 y) were studied retrospectively for a mean follow-up period of 2.7 y (range, 1-12.5 y). An evaluation study consisted of a low-dose 131I diagnostic procedure under hyperthyroid conditions (thyroid-stimulating hormone > 30 MicroU/mL), 201TI scintigraphy, and measurement of thyroglobulin (Tg) under hypothyroid conditions. A total of 254 preablation studies (1 study per patient) and 586 follow-up studies (average number of studies, 2.3 per patient) were evaluated.

Results: Before ablation, low-dose 131I screening was useful to estimate the size of the thyroid remnant. Low Tg levels (<10 pmol/L) indicated the absence of metastases. After ablation, undetectable Tg levels indicated the absence of tumor recurrence. When Tg levels were high (>10 pmol/L), local recurrence or metastases were always observed, providing the basis for additional high-dose 131I therapy. In these patients, 201TI imaging did not provide a significant contribution to patient management. In the case of autoantibodies against Tg, both low-dose 131I screening and 201TI scintigraphy may be advocated to allow an aggressive diagnostic work-up.

Conclusion: Tg plays a key role in follow-up and in making decisions to treat patients with differentiated thyroid carcinoma. The role of 201TI imaging is very limited. In patients with negative low-dose 131I screening, 201TI scintigraphy can be considered when Tg is elevated or cannot be evaluated because of autoantibodies against Tg. Under such circumstances, administration of a therapeutic 131I dose without 201TI imaging can be considered.

MeSH terms

  • Adenocarcinoma, Follicular / blood
  • Adenocarcinoma, Follicular / diagnostic imaging*
  • Adenocarcinoma, Follicular / radiotherapy*
  • Carcinoma, Papillary / blood
  • Carcinoma, Papillary / diagnostic imaging*
  • Carcinoma, Papillary / radiotherapy*
  • Female
  • Follow-Up Studies
  • Humans
  • Iodine Radioisotopes / therapeutic use*
  • Male
  • Middle Aged
  • Postoperative Care
  • Radionuclide Imaging
  • Radiopharmaceuticals
  • Thallium Radioisotopes
  • Thyroglobulin / blood
  • Thyroid Neoplasms / blood
  • Thyroid Neoplasms / diagnostic imaging*
  • Thyroid Neoplasms / radiotherapy*
  • Thyroidectomy

Substances

  • Iodine Radioisotopes
  • Radiopharmaceuticals
  • Thallium Radioisotopes
  • Thyroglobulin