There wasn’t much doubt about the value of colonoscopies, the rather invasive screening tests for colorectal cancer. Now there should be none.

These screenings, unpleasant as they are, do indeed save lives. The New England Journal of Medicine recently reported that in patients tracked for as long as 20 years, the death rate from colorectal cancer was cut by 53 percent in those who had the test and had precancerous polyps removed.

A colonoscopy examines the inside of the large intestine with a tiny camera mounted on a slender tube. It generally takes less than an hour, and patients almost always are out cold for the procedure. While there is always a small chance of complications, most people come out of the examination saying, “It wasn’t nearly as bad as I feared.”

That might not be what they say about the preparation for the exam, which involves a prolonged period of not eating and then drinking a solution that cleans out the bowel.

But at least the medications used to calm people and then put them to sleep for a bit can lead to a solid afternoon’s rest once the procedure is over.

And the peace of mind, particularly for those who are at higher risk because they have had colon cancer in their families, is wonderful. This kind of thorough examination often leads to a “good to go” diagnosis for 10 years.

For those who have had the polyps, examinations will be done more frequently.

The bottom line is simple: This is one form of cancer that can be prevented, if people get screenings before symptoms appear, and start at about age 50. (The age might be younger for those with a family history.) Considering that colorectal cancer is the second- leading cause of cancer deaths in the United States, no one should fear the test so much as to not take it.