Causes Of Leukaemia In N.Z. Sought

Press, Volume XCIX, Issue 29401, 31 December 1960, Page 15

Causes Of Leukaemia In N.Z. Sought

Radiation “seems to be of very small importance indeed” in causing leukaemia in New Zealand, Dr. F. W. Gunz, of the pathology department, Christchurch Public Hospital, said yesterday. For the last three years, Dr. Gunz has been leading an investigation into the case-histories of New Zealand leukaemia patients, to try to trace factors which might be important in causing the disease.

“This is probably our most important conclusion to date, although it is a negative one,” said Dr. Gunz. “It seems to tally with what is being discovered overseas.”

At one time, there had been a widespread fear that the lift in background nuclear radiation after bomb testing might be responsible for the increase in leukaemia reported in many countries. That increase, at any rate as far as New Zealand was concerned, was more likely to be owing in the main to better diagnosis of the disease, Dr. Gunz said.

Other things which might have been suspected to have had an influence on the distribution of leukaemia, but which so far had given no hint of doing so in New Zealand, includes contact with certain chemical substances, including drugs; famjly histories; place of residence; and contact with other sufferers.

The one chemical which was known to have a connexion with leukaemia—the solvent benzol — was subject to strict legal precautions in the Dominion, said Dr. Gunz. He had found no case attributable to benzol in his investigations. A few families had been discovered overseas with what is apparently a hereditary susceptibility to leukaemia, but none had been found in New Zealand. As for contact with sufferers, ‘•there is at the moment no indication that . human leukaemia can be spread by infection,” Dr. Gunz said. In some animals the disease could apparently be caused by viruses, but there was no direct evidence that human leukaemia could be caused by a virus.

As medical knowledge stands at present, leukaemia can, in many instances, be kept in check for some years, and this period is becoming longer. Dr. Gunz believes the time may soon come when treatment may keep most forms of leukaemia at bay indefinitely, as with some other diseases such as pernicious anaemia and diabetes. “Of course, this may only be a pipe dream,” he said. New Cases Each year, between 150 and 200 new cases of leukaemia were notified to him, said Dr. Gunz. About 30 of these were in children under five, and most of the rest were persons over 50. There were several distinct types of leukaemia, some of them, Dr. Gunz said, apparently blood-cancers, but others almost certainly a different origin. Some forms were a “short, sharp, and fatal” disease, but in other cases, especially in elderly persons, the affliction could be “quite mild,” not necessarily shortening the life of the patient.

In most cases —about 95 per cent.—the disease was immediately recognisable when a sample of the patient's blood was examined under the miscroscope. In others, extensive clinical tests might be necessary to identify the disease. In all cases, however, laboratory tests were necessary for diagnosis, which. Dr. Gunz said could well be the main reason why there were fev cases of leukaemia reported from backward communities.

One form of leukaemia seemed to be almost absent in many nonwhite races. This was probably responsible for a slightly lower over-all incidence of leukaemia among the Japanese than among Europeans. Dr. Gunz said he was having difficulty in obtaining comprehensive statistics about

leukaemia among the Maoris, but he found some indication that they also might be relatively free of the one type of leukaemia. White Blood-cells Leukaemia waS characterised, in general, by a large increase in the number of white blood-cells. “It looks as if the tissues producing the white cells carry on doing so when they have no business to,” said Dr. Gunz. “Whatever checks them from over-producing in a normal person seems to be ineffective in a leukaemia patient.” To try to trace the cause of the over-produbtion, Dr. Gunz has arranged a new project, the examination of the nuclei of the cells of the bone-marrow and other white-cell producing areas. The nuclei will be examined for chemical abnormalities and for aberrations in the number of chromosomes in the cells. For this work, a special research fellow has been appointed to work under Dr. Gunz by the British Empire Cancer Campaign Society. f r The appointee, Miss Angela Adams, a Dunedin biologist, will start work at the end of February in a new laboratory provided by the North Canterbury Hospital Board, next to Dr. Gunz’s office. As a preparation for her work, she is being sent to study for a short time under Professor H. N. Robson, of the University of Adelaide. Dr. Gunz’s work so far has been financed by the National Cancer Institute of Washington.