RADIONUCLIDES AND THERAPY OF THYROID-CANCER

The majority of thyroid carcinomas are removed surgically. The appropr iate surgical technique is still debated. After surgery the amount of residual thyroid or tumour and the presence of local or distant metast ases is often in doubt, particularly if it is not detectable clinicall y. Therefore, methods for determining the presence of disease or the l ater recurrence of disease are needed. They commonly include serum thy roglobulin and imaging after diagnostic or therapeutic doses of I-131. Other techniques are used such as I-131 whole body retention (using a whole body counter), Tl-201 and Tc-99m-sestamibi imaging. The place o f these diagnostic methods in the management of thyroid cancer is revi ewed in this article. Radioiodine would seem an ideal treatment for re currence of functioning thyroid carcinoma as I-131 targets the lesion and has minimal side effects. However, the indolent nature of well-dif ferentiated thyroid carcinomas makes it difficult to assess the benefi ts of radioiodine therapy both in its ability to ablate the normal thy roid and to treat recurrent and metastatic disease. However, the addit ion of radioiodine therapy to local surgical removal reduces both the occurrence of metastases and the morbidity with prolonged follow-up. U nresolved issues that remain concern the activities of radioiodine nee ded to achieve adequate ablation of residual thyroid tissue and to tre at residual and recurrent cancer. There is also debate as to exactly w hich patients require radioiodine therapy. This review also considers radiation protection and the side effects of I-131 therapy.