text:  Dr. Campbell also told us that people under the age of 50 need to be aware of potential symptoms and see a doctor if they're having any kind of abdominal pain, blood in the stool, unintentional weight loss, that kind of thing. Dr. Rebek, let me first hear from you on this. It's interesting to me that he said that early and later, colorectal cancer at least, they look very similar under a microscope and molecularly. What's significant about that?