IN CONFIDENCE ~5~ (ii) A temporary cessation of this administration of Synthroid is necessary wnen tests for remaining activity are needed in patients who have been treated for thyroid cancer, as was done in the four affected patients in 1968. The period of withdrawal then used was in my view longer than needed and I have discussed this point with Dr. Conard. I find that 1 month is needed, whereas 3 months were used (1 of which apparently arose from delay in travel of patients for the tests). The effect of this would not be, and evidently was not, substantial in causing return of any severe hypothyroid symptoms, and at least it will have made tests to exclude the persistence of tumour tissue more rigorous. (iii) The administration of thyroxine preparations to decrease the likelihood of nodules developing is also generally accepted practice, and the dosages used are normal ones. The basis for this practice is a theoretical one (to avoid stimulation of the thyroid cells by the body's own production of thyroid stimulating hormone) and it is not known by experience how fully effective it is. It cannot be completely effective, since a nodule has appeared this year in a young woman wWio was receiving this treatment. (iv) The removal of "solitary" nodules is normal medical practice if they arise spontaneously, particularly in younger people and often also in older people if they do not decrease after thyroxine administration. When they arise after thyroid irradiation, and if onlv occurring rarely in unirradiated people of the same race and way of life, there is a much stronger case for removal to exclude possible malignancy. 2(b). Present and proposed treatments continuing on these lines appear appropriate and adequate. I agree with the opinion in the team that the nodules newly detected in two young people (by the time of my leaving Majuro) should be removed surgically, with whatever removal of thyroid tissue or local lymph nodes is indicated by their histological nature (benign or malignant). A particular problem comes up in testing for the completeness of removal of any malignant thyroid tissue. All the four people from whom thyroid cancers have been removed were examined in detail at the time of operation, and by clinical examinations since, to exclude any remain- ing tumour tissue, and no evidence has been found of any. They have in addition had scans in 1968 which are reported as showing no concentration of radioiodine in any position which would necessarily indicate tumour tissue to be remaining, no uptake having apparently been found except in positions consistent with remaining normal tissue. I have discussed in detail with Dr. Conard certain additional and sensitive tests that we currently use in this situation, but these might present greater difficulties than those already used, either because of the high concentrations of a characteristic iodoprotein which is present normally in the blood 226 / continued...