Chemical safety: a global challenge.

Tumour radioiodine concentration has been compared with serum thyroglobulin (Tg) and, in a few cases, with tumour complement of thyrotrophin receptors in patients with differentiated thyroid carcinoma. All tumours examined possessed TSH receptors. In most the complement was similar to that of normal thyroid tissue although all but one of the tumours had no detectable 1311 concentration in vivo even with excess TSH stimulation. Elevated serum Tg (patient taking T4 in suppressive dose) was generally associated with tumours which had 1311 concentrating function when stimulated by excess TSH. Some patients, however, had high serum Tg concentration but only low or indetectable tumour 1311 uptake. We conclude that (a) measurement of tumour TSH receptor complement is unlikely to be useful in clinical management as tumours which do not significantly concentrate 1311 in vivo may have a normal TSH receptor complement and (b) the capacity to secrete Tg is usually associated with 1311 concentration but quantitatively the relationship varies considerably between tumours. For the effective use of 1311 in the treatment of thyroid cancer, adequate organification of the radioisotope by tumour tissue is essential. Most thyroid tumours even though differentiated, are usually nonfunctional initially when normal thyroid tissue is still present. Subsequently a tumour often develops the ability to concentrate 1311 although usually only if stimulated by supranormal levels of TSH (Edmonds et al., 1977). Unfortunately there is no satisfactory way of predicting at an early stage whether a particular tumour will eventually develop sufficient capacity for 1311 concentration. Thyro-globulin production and the presence of TSH receptors on the plasma membranes are two properties indicative of potentially functioning tissue and we have compared these characteristics with the radioiodine uptakes observed during treatment. Materials and methods All patients attended the Thyroid Clinic in the Department of Radiotherapy and Oncology at University College Hospital and were subsequently on long term follow up. The treatment protocol was initial thyroidectomy with removal of as much tumour as possible followed by therapy and test doses of 1311 as previously described (Edmonds et usually 200-300,ug sufficient to suppress the TSH response to TRH. The T4 was stopped 4 weeks before an 1311 dose. Treatment and test doses of 5.5GBq (lOmCi) and 185MBq (5mCi) of 1311 respectively were used. A whole body profile scanner based on the design of Corbett et al. (1956) but having a sodium iodide scintillator with a rectangular slit collimator perpendicular to the long axis …