Regular
consumption of caffeinated coffee may help prevent the return of colon cancer
after treatment and improve the chances of a cure, according to a new, large
study from Dana-Farber Cancer Institute that reported this striking association
for the first time.
The
patients, all of them treated with surgery and chemotherapy for stage III colon
cancer, had the greatest benefit from consuming four or more cups of coffee a
day (about 460 milligrams of caffeine), according to the study published in the
Journal of Clinical Oncology. These patients were 42 percent less likely
to have their cancer return than non-coffee drinkers, and were 33 percent less
likely to die from cancer or any other cause.
Two to
three cups of coffee daily had a more modest benefit, while little protection
was associated with one cup or less, reported the researchers, led by Charles
Fuchs, MD, MPH, director of the Gastrointestinal Cancer Center at Dana-Farber.
First author is Brendan J. Guercio, MD, also of Dana-Farber.
The
study included nearly 1,000 patients who filled out dietary pattern questionnaires
early in the study, during chemotherapy and again about a year later. This
"prospective" design eliminated patients' need to recall their
coffee-drinking habits years later -- a source of potential bias in many
observational studies.
"We
found that coffee drinkers had a lower risk of the cancer coming back and a
significantly greater survival and chance of a cure," Fuchs said. Most
recurrences happen within five years of treatment and are uncommon after that,
he noted. In patients with stage III disease, the cancer has been found in the
lymph nodes near the original tumor but there are no signs of further
metastasis. Fuchs said these patients have about a 35 percent chance of
recurrence.
As
encouraging as the results appear to be, Fuchs is hesitant to make
recommendations to patients until the results are confirmed in other studies.
"If you are a coffee drinker and are being treated for colon cancer, don't
stop," he said. "But if you're not a coffee drinker and wondering
whether to start, you should first discuss it with your physician."
Fuchs
said the study is the first to study an association between caffeinated coffee
and risk of colon cancer recurrence. It adds to a number of recent studies
suggesting that coffee may have protective effects against the development of
several kinds of cancer, including reduced risks of postmenopausal breast
cancer, melanoma, liver cancer, advanced prostate cancer.
Fuchs
said the research focused on coffee and other dietary factors because coffee
drinking -- in addition to possibly being protective against some cancers --
had been shown to reduce the risk of type 2 diabetes. Risk factors for diabetes
-- obesity, a sedentary life style, a Western diet high in calories and sugar,
and high levels of insulin -- are also implicated in colon cancer.
In
analyzing the results of the new study, Fuchs and his colleagues discovered
that the lowered risk of cancer recurrence and deaths was entirely due to
caffeine and not other components of coffee. He said it's not clear why
caffeine has this effect and the question needs further study. One hypothesis
is that caffeine consumption increases the body's sensitivity to insulin so
less of it is needed, which in turn may help reduce inflammation -- a risk
factor for diabetes and cancer, Fuchs said.
Other
than drinking coffee, Fuchs said, people can take other measures to reduce
cancer risks -- avoiding obesity, exercising regularly, adopting a healthier
diet, and eating nuts, which also reduce the risk of diabetes.
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