Leukaemia May Have String Of Causes

Press, Volume CIV, Issue 30822, 6 August 1965, Page 14

Leukaemia May Have String Of Causes

Known causes of leukaemia accounted for less than 10 per cent of the cases which occurred, said Dr. F. W. Gunz, of the pathology department of the Christchurch Hospital, in a lecture to the Canterbury branch of the Royal Society of New Zealand. There was a good deal of evidence now, he said, that there was not just one cause of the disease but a whole string of causes, each one coming on top of the previous one. These causes could be quite common and übiquitous agents. Measles, for example, was known to cause chromosome changes, and if there had already been other changes in a cell, measles could be the one to start leukaemia. “It is now widely believed that many different agents can push the cells over the edge, once the soil has been prepared,” said Dr. Gunz, incidence in N.Z. He said the incidence of the disease in New Zealand was seven or eight for every thousand deaths. It was not, as was commonly believed, a cancer of the blood, but a dis-

ease of the organ which formed the blood—chiefly the bone marrow which made the blood cells and turned them out into the blood-stream. Dr. Gunz said that while the number of deaths from leukaemia tn New Zealand had doubled, and risen a little more steeply than the population increase, between 1936 and 1960, the number of pathologists had gone up even faster. “The more people you have to diagnose the disease,” he said, “the more cases will be reported. This partly, if not largely, explains the rise in the disease, and it is largely fictitious.” He said that one of the most striking facts that had to be explained was that of the 125 children who died from leukaemia in New Zealand between 1956 and 1960, most were in the group aged one to four. There was also a misleading appearance of a greater incidence of leukaemia in aged Maoris than in aged pakehas. This was explained by the fact that there was a different age distribution in the two races. There was a smaller proportion of aged persons in the Maori population than in the white population.

Some Apparent Causes Dr. Gunz listed as the apparent causes of some cases of leukaemia genetics, mongolism, infection, and ionising radiation. But in each case only a minute number of the persons affected by those factors contracted leukaemia. If leukaemia could be caused genetically, more members of any one family could be expected to get it than was so; if mongolism was a cause, why did not more mongols get leukaemia; if infection was a cause in itself, why were there only tiny pockets of cases close together; if radiation was a cause in Itself, why did not all of those near the centre of the 1945 atomic explosions in Japan get leukaemia? Dr. Gunz said these were the reasons for the belief that there must be many causes of the disease, accumulating one on top of another.