Colon Cancer Prevention Fits Into Healthy Lifestyle

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. "Let’s 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 that’s 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 nation’s overall health.

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 can’t predict which individuals will get cancer.

"Colon cancer is the second leading cause of cancer death in the United States, and it’s largely preventable," Dr. Colditz said, "but there’s little interest in stopping it. We have to work with the media, health care providers, and legislators to change this."

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.