Chromosomal damage in human lymphocytes from radio-isotope therapy.

Much interest has been shown in recent years in the use of chromosomal damage in human circulating lymphocytes as an indicator of absorbed dose of external ionizing irradiation (Evans, 1967; Bender and Brewen, 1969; Dolphin, 1969; Scott, Sharpe, Batchelor, Evans, and Papworth, 1970). Because of the long mean life of such lymphocytes, induced damage is detectable many years after exposure, making it possible to assess dosage retrospectively, where reconstruction ofdamage in radiation accidents by physical methods has been difficult or impossible (Purrott, Lloyd, Dolphin, Eltham, Platt, Tipper, and Strange, 1973). However, surprisingly little has been reported on the effects of therapeutic administration of radioisotopes. Indeed, before the study of patients who had had intra-articular injections of 198Au, there appear to have been only two papers on patients with polycythaemia vera treated by phosphorus 32 (32p), and half a dozen reports on patients treated by iodine 131 (1311) for the control of hyperthyroidism or by ablation doses in the therapy of thyroid cancer. None of these papers satisfy certain criteria, including numbers of patients, and numbers of cells examined, which are essential for examination of dose-damage relationship, and in most, including understandably the earlier studies, the techniques used and the methods of scoring and presentation of data, do not meet the requirements suggested in UNSCEAR (1969). The present paper considers five sets of data accumulated in the MRC Population Genetics Unit in Oxford since 1971. Those relating to patients treated by intra-articular injections of 198Au or 90Y, which have already been published (Stevenson, Bedford, Hill, and Hill, 1971b; Stevenson, Bedford, and 11 others, 1973), and unpublished data from a further series of ten patients of Dr. F. M. Andrews of Reading who had intra-articular injections of 90Y, twelve patients treated by Prof. J. B. Kinmonth and his colleagues in St. Thomas' Hospital byendolymphatic injections of 32p labelled lipiodol, and 28 patients treated by Dr. G. Wiernik and his colleagues in the Churchill Hospital, Oxford, with 131I for hyperthyroidism. I am indebted to these colleagues for permission to quote the data, and to Dr. Nora Blackwell, of this Unit, who analysed the cells from the iodine-treated patients. Clearly, in a short contribution to a symposium, it is impossible to present data in full, or to discuss them alone or in association with the literature. There is no need to consider the findings in the first series of 198Au and 90Y patients, as the data have been presented in full in the Annals of the Rheumatic Diseases. However, the use by rheumatologists of colloidal suspensions of particulate 198Au and 90Y presented a unique opportunity to study one aspect of chromosomal damage from radio-isotopesnamely, the effects of distribution in the body on the types of tissue absorbing released energy and the coright.