[ RadSafe ] " Rich kids face higher risk of leukemia "

[Jaro]

http://www.canada.com/montreal/montrealgazette/news/story.html?id=d9096228-4
a32-4c8c-a949-83fdd1f56b3a

Rich kids face higher risk of leukemia

Study by B.C. Cancer Agency. Work buttresses theory most recently discussed
in British medical journals

PAMELA FAYERMAN   CanWest News Service, June 23, 2005


Children living in Canada's most affluent neighbourhoods have a higher risk
of developing leukemia compared with those living in the poorest
neighbourhoods, according to the largest Canadian study ever done on
socio-economic status and childhood cancer risk factors.

The study by B.C. Cancer Agency researchers, which will appear in the July
issue of Epidemiology, looked at 5,240 cases of leukemia in children
diagnosed between 1985 and 2001 in 10 provinces. Using provincial cancer
registries, postal codes, 1996 census data and neighbourhood income averages
from Statistics Canada, the researchers found the lower risk in the poorest
neighbourhoods was restricted to children diagnosed with acute lymphoid
leukemia (ALL), the most common and the most treatable type of leukemia.

Children living in the poorest neighbourhoods across Canada had a
14-per-cent lower risk of developing ALL compared with children in the
richest neighbourhoods. For the rarest subtypes of childhood leukemia
(chronic or acute myeloid and acute nonlymphocytic), the risk was weaker and
less precise.

Researchers divided the population into five income classes, with each class
representing about one-fifth of the population. The mean income of
individuals living in the poorest neighbourhoods was $22,049, based on 1996
census data, while the mean income of individuals living in the most
affluent neighbourhoods was more than double, at $50,284.

Marilyn Borugian, the epidemiologist who was the lead investigator of the
study, said in an interview that the work buttresses the theory most
recently discussed in British medical journals that leukemia is more likely
if there is an absence of exposure to various infections early in life. She
said in the poorest, most crowded neighbourhoods, there may be more exposure
to bacterial and viral infectious agents that may confer some protection on
children.

In a 2002 study in the British Journal of Cancer, California researchers
showed delayed exposure to common infections may play a role in the
development of leukemia. In that study, children in day cares had a lower
incidence of leukemia, compared with children who had never attended a day
care.

"Such an association may be explained by the protective effect of early
exposure to common infections among day-care attendees," Borugian and her
co-authors say.

Paul Rogers, head of pediatric oncology at B.C. Children's Hospital, said
while the association between exposure to infections and the lowered risk of
leukemia is increasingly being considered, "it remains unproven."

About 1,285 children are diagnosed with cancer each year in Canada.
Leukemia, which is the most common of childhood cancers, accounts for 26 per
cent of new cancer cases. ALL is the most common subtype, but because of
progress in treatment regimes, about 80 per cent of children are now cured.

Vancouver Sun

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