A new study finds cases of colon cancer for people younger than 50 has gone up over the past decade. The study, published in the journal Cancer, looked at trends in colon cancer rates. While cases among people 50 and older are declining, rates are rising for those under 50, from 10 percent of all cases in 2004 to around 12 percent in 2015.

CBS News chief medical correspondent Dr. Jon LaPook said the decline in patients over 50 is due to the success of screenings like colonoscopies, which spot polyps that can be removed before they become cancerous. But the trend showing an increase of cases for patients under 50 can't be easily explained.

"The most intriguing possibility to me is it has something to do with the gut microbiome," LaPook said. "That's the trillions of bacteria and hundreds of species in our gut. And it turns out that certain species are linked to increased risk of colon polyps and colon cancer. Maybe we're messing up our gut microbiome with antibiotics and our modern diet."

According to the National Cancer Institute, colon cancer is the fourth most common cancer and the second deadliest type of cancer behind lung cancer. The American Cancer Society has lowered its recommended age for initial screeningsfrom age 50 to 45. But as Dr. LaPook explains, other organizations haven't followed suit. He said the decision to get screened should be made between a patient and their doctor.