PART II OF VI
JULY 25, 2005
WEALTH AS A CANCER RISK
By David Secko
Wealth can bring a lot of things to a family and new research is suggesting such things are not always good.
One of these is childhood leukemia.
Although rare overall, leukemia is one of the most common potentially fatal illnesses that can befall a child, and a new study completed at the BC Cancer Agency in Vancouver is revealing that a high socioeconomic status can raise the risk of this disease by as much as 14% in Canada.
The reasons for the link between wealth and childhood leukemia are not yet clear, but knowing is important nonetheless, since its a piece of the puzzle in the effort to understanding the true causes underlying this disease, which are not well understood.
Money doesnt cause disease, says Marilyn Borugian, a researcher at BC Cancer Agency and lead author of the new study. But there are so many things related to it.
Borugian and colleagues work is not the first to link childhood leukemia to high socioeconomic status. In fact, reports go back at least two decades.
But, in recent years, work on the effect of power lines on childhood cancer (by one of the authors of the current study, Mary McBride) appeared to find that the opposite was true, namely that childhood leukemia instead associates with lower, not higher, income.
They [McBride and colleagues] found that the healthy children seemed to be of higher income, says Borugian, referring to the past studies. So, a question was afoot: has something changed? Or, was their an unseen bias in the power line studies?
About this time, Borugian got recruited to find the answer. She was just finishing her Ph.D., having come to study epidemiology after a 25 year career in computing for a stock brokerage. We wanted to go about this new study through computer programming, says Borugian, so thats how I got involved.
To re-examine the link between childhood leukemia and wealth, Borugian took Canadian postal codes and linked this to information from Statistic Canada on neighborhood incomes and 96% of all leukemia cases in children from 1985-2001. She found the lowest risk of childhood leukemia in the poorest neighborhood income and the highest risk in the richest.
The original studies, with a higher risk in a higher income, are still supported, says Borugian. The results of the study appear in July issue of Epidemiology.
Apart from this result, Borugians general technique is also raising interest. It is already being used to look into other cancers, she says.
As for the risk of childhood leukemia, population studies like Borugians dont reveal causes. People have hypothesized that early exposure to childhood infection in poorer neighborhoods might provide protection, says Borugian, but researchers need to zero in on individual cases to figure this out.
In order to do something about this, there are still a couple pieces missing, says Borugian, including individual studies to control for things such as diet and exercise.
It may be as simple as increased physical activity in poorer families, she says. But, as yet, we dont know.
David Secko is a molecular biologist and a science writer, who is currently studying journalism at the University of British Columbia. He thinks Steven Wright was right when he asked: "ok, so what's the speed of dark?" His writing has appeared in The Scientist, The Tyee, Canadian Medical Association Journal, Science's Next Wave and UBC's Thunderbird Magazine.
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