BETHESDA--Diet, physical activity, obesity, and aspirin use all
influence the risk of colon cancer, according to both the underlying
biology and evidence from epidemiologic studies, Graham Colditz, MD,
DrPH, associate professor of medicine, Harvard Medical School, said
at the American Society of Preventive Oncology (ASPO) annual meeting.
Typically, Dr. Colditz said, only one risk factor is studied at a
time, but risk factors tend to cluster. For example, a subject with
low socioeconomic status (SES) may also smoke, be overweight, and
consume fewer fruits and vegetables than one of higher SES. "We
must combine individual change, environmental strategies, and policy
initiatives," he said.
At the same time, Dr. Colditz is concerned about overloading the
public with warning messages, to the point that the population tunes
out. Early smoking and alcohol use increase colon cancer risk, but
adding colon cancer to existing antismoking or antidrinking messages
is unlikely to increase their impact.
"We have to move to a new view of wellness," he said.
"Lets get away from seeing one cause for one disease."
More important is finding an integrated view of a healthy life and
then getting people to adopt and sustain it.
Most benefits from lifestyle changes are modest in scale. Using
aspirin might cut colon cancer risk by 50%--but thats about the
biggest effect, he said. However, cutting down on red meat and
alcohol, and increasing consumption of fruits and vegetables, across
the population could have a substantial effect on the nations
On an advocacy level, Dr. Colditz said, science has trouble
documenting who did not get cancer as a result of prevention
efforts. "Prevention is a nonevent, compared to treatment,"
he said. The long lead-time for many cancers--decades from preventive
intervention to actual benefit--means that urgency for change is
lacking. Epidemiology is good on the population scale ("How many
will get the disease?"), he said, but cant predict which
individuals will get cancer.
"Colon cancer is the second leading cause of cancer death in the
United States, and its largely preventable," Dr. Colditz
said, "but theres little interest in stopping it. We have
to work with the media, health care providers, and legislators to
He suggested emphasizing positive behaviors rather than trying to
stamp out "bad" ones. "Health care providers should
counsel, not give scare talks," he said, "and recognize
that behavioral change is outside conventional medical control."
As an example of a "positive" effort, he cited this three-pronged
strategy for increasing physical activity:
Health care providers should not only counsel patients about the need
to exercise but should set a good example by increasing their own
activity level and avoiding weight gain.
Policy makers should allow school gyms to stay open on weekends for
all citizens or develop bike paths along old railroad beds.
Individuals can buddy up for walking or volunteer as gym supervisors.