Drinking coffee regularly might protect smokers
from bladder cancer, a new study suggests, finding that bladder
cancer was about half as likely to occur in smokers who regularly
drank coffee as in smokers who did not.
``This could suggest that the coffee consumption modifies the
effect of tobacco smoking,'' said Dr. Gonzalo Lopez-Abente, the
Spanish researcher who led the study, published this week in the
London-based Journal of Epidemiology and Community Health.
Experts not connected with the research had mixed reactions to
the findings, however, ranging from the view that they highlight
the often-unexpected protective benefits of substances found in
food to the opinion that the study's methodology was flawed.
All agreed, however, that the best way to reduce the chance of
getting bladder cancer is to stop smoking.
In the study, smokers who drank coffee still had triple the
chance of developing the disease as nonsmokers who drank coffee.
But smokers who didn't drink coffee were seven times as likely to
get the disease as nonsmokers who did not drink it.
The possibility that coffee-drinking might offer some protection
to smokers ``arose some years ago when we had observed that there
could be a little increase of bladder cancer risk for coffee
drinking, but this risk was only observable in nonsmokers,'' said
Lopez-Abente of the Carlos III Health Institute in Madrid, Spain.
Smoking is recognized as a leading cause of bladder cancer.
Experts estimate that about 50 percent of these cancers in men and
30 percent in women are due to smoking.
Cigarette use increases the risk for bladder cancer by two to
five times and, when smokers quit, their risk declines in two to
four years, according to the U.S. National Cancer Institute.
The Spanish study involved 497 people with bladder cancer, who
were compared with 1,100 people without the disease. They were all
asked about their smoking and coffee-drinking habits. Those who
drank less than two cups of coffee a week were classified as
``The mechanisms suggested for the apparent protective effects
of coffee are quite plausible,'' said Ian Johnson, head of
intestinal physiology and cellular metabolism at the Institute of
``But it is worth noting that substances found in vegetables
like broccoli and brussels sprouts exert similar biochemical
effects, and may be even more protective against tobacco-related
cancers,'' Johnson said.
Dr. Robert Huddart, a cancer expert at the Royal Marsden
Hospital and the Institute of Cancer Research in London said the
study raises an interesting hypothesis that needs to be tested by
other scientists before real confidence can be placed in it.
Dr. Annie Sasco, chief of epidemiology for cancer prevention at
the International Agency for Research on Cancer, part of the World
Health Organization, was less impressed.
``It sounds a little bizarre,'' Sasco said. ``There is nothing
about potential other sources of caffeine, such as tea and
Coca-Cola, and it's very strange to categorize people who drink two
cups of coffee a week as non-coffee drinkers.''
``I don't find it very convincing at all,'' she said.