Many experts now consider colon cancer a largely preventable disease, but a new study finds that primary care doctors might not always inform patients about one important step they can take to reduce their risk -- becoming more physically active.

Co-author Elliot Coups of the Fox Chase Cancer Center in Cheltenham, Pa., analyzed survey data from 1,932 adults who answered questions about colon cancer risks and only 15 percent listed physical activity as a means of reducing their risk.

However, a sedentary lifestyle accounts for as many as 14 percent of all colon cancer cases in the United States, but highly active individuals have a 30 percent to 40 percent lower risk of developing colon cancer, the researchers said.

Coups said doctors might find it easier to promote the general benefits of exercise -- without specifically mentioning colon cancer -- even to a patient who has a family history or other risk factors for the disease.

The study appears in the August issue of the journal Patient Education and Counseling.