The most common answer:

"Making the following lifestyle changes can help you prevent colorectal cancer, and lead to a healthier life:
Get five servings of vegetables, fruits, and whole grains a day.
Limit red meat and saturated fat.
Exercise five days a week for at least half an hour.
Quit smoking.
Avoid alcohol.
Maintain a healthy weight.
Screening for colorectal cancer is a very important prevention factor."

Source: Men's Health - Top 10 Health Concerns of Men - Cancer
Although I've seen this info in a number of other places.

Aloha,
RH