Actors Ryan Reynolds and Rob McElhenney invited cameras to document their first colonoscopies to raise awareness for colorectal cancer screening.

“Part of being this age is getting a colonoscopy,” says Reynolds, who turned 45 this year. “It’s a simple step that could literally—and I mean literally—save your life.”

Jonathan LaPook, MD, the Mebane Professor of Gastroenterology at NYU Grossman School of Medicine and CBS News chief medical correspondent, says the recommended age for people of average risk to get their first colonoscopy—the most comprehensive screening test for colon cancer—changed from 50 to 45 because colon cancer is becoming more prevalent in people under age 50.

“If you have symptoms, go to your healthcare provider and get them evaluated earlier,” says Dr. LaPook, also a gastroenterologist with NYU Langone’s Colon Cancer Screening and Prevention Program. “If you have a change in your stool—and you have to get specific—if you notice bleeding, if you notice narrowing of the stool, if you have abdominal pain, if you’ve been told you have iron deficiency, anemia, you’re tired because of that, it could be because of invisible blood loss because of a polyp or an early cancer that you don’t even know about.”

In Reynolds’s case, Dr. LaPook removed a subtle polyp that potentially could have turned into cancer over time.

“That is exactly why you do this,” says Dr. LaPook. “You find it, you pluck it out, and instead of potentially getting cancer, you don’t get cancer.”

Watch more on CBS Mornings.