Ever since she lost her husband, Jay, to colorectal cancer in 1998, Katie has been a staunch advocate for awareness and early detection. Sadly, since Jay’s passing at 42, the number of cases among young people has risen dramatically. The disease is now the deadliest form of cancer for men under 50, and the second leading cause of cancer death for women under 50.

What’s behind this disturbing trend? We turned to Andrea Cercek, MD, to find out. Dr. Cercek is an oncologist at Memorial Sloan Kettering and the founder and co-director of the Center for Young Onset Colorectal and Gastrointestinal Cancer, a first-of-its-kind clinic dedicated to treating young patients.

“We’re seeing more and more young people being diagnosed, and this has been happening since the mid-1990s,” Dr. Cercek tells Katie. “I think what’s scariest is that this is not unique to the United States, or other developed countries. It’s really happening all over the world.”

In this new interview, Dr. Cercek discusses some of the theories behind why the disease is striking so many people in the prime of their lives, some of the cutting-edge treatments on the horizon, and much more. Watch the full conversation in the video above.