It can be uncomfortable, and that may explain why 40 percent of Americans 50 years old and above don't get a colonoscopy.
"I didn't enjoy mine, but I was glad I had it done. They're just important to do," said Sherri Vance.
The 55-year-old said she would rather be safe than sorry, but she knows cancer screening tests have come under scrutiny recently.
In October, a government panel recommended men should no longer get the P.S.A. blood screening test for prostate cancer after concluding it didn't save lives. In 2009, another expert panel caused an uproar when it recommended women get mammograms at age 50 instead of 40.
"I don't know how helpful all these screenings really are. I don't know if it's just a way to get our money," Vance said.
But ABC's Dr. Mehmet Oz sides with new guidelines from the American College of Physicians that enforces colon cancer screenings start at age 50 and then every ten years after that until age 75. A new study in the New England Journal of Medicine found colonoscopies in which doctors found and removed pre-cancerous growths reduced colon cancer deaths 53 percent.
"Unlike a lot of screening tools, like mammography, that tell you about a mass but don't solve the problem for you, when you have a colonoscopy, when you find something like a polyp - like they found in me - you take it out and you're done,' Dr. Oz said.
For the person who has a higher risk of colon cancer, such as having a close family member diagnosed, the American College of Physicians recommends starting at age 40 or 10 years before the youngest relative was diagnosed, then it's suggested to go every five years.
While no test is perfect, Dr. Oz says what holds people back is not the fear of the test, but fear of the results. But that shouldn't stop you.
"Find it out and you have an obligation to your family," Dr. Oz said. "Not to yourself, to your family, to get the results and address it."