One in 20 Americans will develop colorectal cancer. About 140,000 cases are diagnosed in the United States each year, resulting in about 49,000 deaths, according to the National Cancer Institute. It is the third most common cancer worldwide.

The U.S. Preventive Services Task Force, a government-backed agency, recommends screening for people age 50 to 75 years by one of three methods: a colonoscopy every 10 years; annual stool testing; or a less-thorough look into the colon (known as flexible sigmoidoscopy) every five years in conjunction with stool testing every two to three years.

People often find the tests unpleasant. For example, in the new study that compared stool testing with colonoscopy, only 34 percent went along with stool testing. The participation rate was even lower when colonoscopy was offered, even though doctors can use it to cut away those suspicious precancerous adenomas.