Some cancer patients are calling on the medical community to screen younger people for colon and rectal cancers, which usually aren't a concern until someone is much older.

Alarming research published last week shows colon and rectal cancer rates rising sharply among people in their 20s and 30s.

Cancer was pretty much the last thing on anyone's mind when Kerryn Miller went in for a colonoscopy following a year of digestive problems.

“I know there were a few people in the room and there were gasps,” she recalled. “I saw the tumor. The colon is very uniform, so when it came up on the screen, it was very noticeable. And then I heard people in the room saying like, ‘Wait, how old is she?’”

Miller was just 24, battling a disease that doctors don't usually screen for until someone is twice that age.

“I think everyone was pretty shocked, and even seeing my oncologist, I was the youngest person in that waiting room by probably 30 years,” she said.

Doctors surgically removed the tumor and put Miller on six months of chemotherapy.

That was eight years ago. Miller is cancer free today, but she wishes she hadn't waited so long in those first few months to speak up and insist that something was wrong.

“I've known a lot of people who weren't taken seriously or who didn't go to the doctor as quickly as I did, therefore had a later stage, and it breaks my heart when they lose the battle. And that's why I'm here is to advocate for those people. It's like know the symptoms, know your body, take yourself seriously, so doctors will also do the same,” said Miller, who found a community of young colon and rectal patients called The Colon Club.

She hopes new research showing a startling rise in colon and rectal cancer rates among millennials will help bring more attention to a disease that might have seemed impossible.

“It really opened my eyes, and there's not a day that goes by that I don't appreciate everything I have,” she said.