asthma and hayfever--the bright side

[Guest guest]

Apparently people who have asthma and hay fever have an 18% less

chance of dying from leukemia and those with just asthma have a 25%

less chance of dying from it.

Tracey

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Asthma, hay fever cuts risk of dying of cancer

study: 12% overall reduction in death rate, U of O analysis finds

Joanne Laucius

The Ottawa Citizen

Wednesday, August 03, 2005

Good news for those who wheeze and sneeze -- having asthma and hay

fever appears to reduce the overall risk of dying of cancer, says a

study led by researchers at the University of Ottawa.

The researchers crunched numbers from an American Cancer Society

database of 1.1 million people and found that those with asthma and

hay fever were 12 per cent less likely to die of cancer.

The inverse relationship between asthma and hay fever and cancer was

even more significant for specific types of cancer, said lead

researcher , an epidemiologist at the McLaughlin

Centre for Population Health Risk Assessment at the University of

Ottawa.

For example, there was a 24-per-cent reduced risk of colorectal

cancer death for those who reported asthma and hay fever, the

researchers reported in the Aug. 1 edition of the American Journal

of Epidemiology.

There was a 14-per-cent reduced risk from pancreatic cancer, a 16-

per-cent reduced risk of ovarian cancer death and an 18-per-cent

reduced risk of leukemia death. The reduced risk of leukemia death

was 25 per cent for those who reported asthma, but not hay fever.

The figures for some other types of cancer were less conclusive.

There was 14 per cent less risk of dying of breast cancer, for

example, a figure Ms. says is " interesting, " but not

statistically significant. There was also a 17-per-cent reduced risk

of people dying from lung cancer if they had asthma and hay fever,

but this is likely because people with these conditions are less

likely to smoke or to smoke heavily.

Even when smoking was taken out of the equation, people with asthma

and hay fever remained at a reduced risk of dying from cancer. Among

non-smokers with asthma and hay fever, there was 22-per-cent lower

risk of dying of colorectal cancer, compared with the general

population of non-smokers.

Researchers have suspected for some time there was some sort of

inverse relationship between cancer and allergies, said Ms. .

" There are a lot of studies out there. When we did a search, we

found over 100 studies dating back to the '60s. "

But a potential link between allergies and cancer remains

controversial. And most other studies were limited in scope.

" This is really huge for an epidemiology study, " said Ms. .

The University of Ottawa study tapped into the massive information

in the American Cancer Society's cancer prevention study, which

offers a database of information on 1.1 million participants over

the age of 30 who had never had cancer when the study began in 1982.

The participants filled out a questionnaire about their health and

lifestyle. The American Cancer Society has been following the causes

of death through the U.S. national death index.

Researchers believe there are several explanations for reduced

cancer risk among people with asthma and hay fever.

" People with allergies have a different immune function. It may be

enhanced. They may be able to detect cancer cells better, " said Ms.

.

Environmental and lifestyle factors could also come into play.

People with asthma and allergies are probably more likely to avoid

pollutants.

There were also limitations in this study. The participants, not

doctors, reported their asthma or hay fever, said Ms. . And

the Cancer Care Prevention Study only tracks deaths, not cancer

diagnoses, which may tell a different story.