I have read many people write about how they or people they know have Stage 4 colon cancer and never had any symptoms. how is this possible? how could someone be completely healthy, have a perfect CBC,etc and yet have something that could potentially kill them in a short span?

In most cases, there are symptoms, especially with men, who don't want to whine or appear wimpy about it. And women can sometimes assume it's related to aging or some sort of female issue. And even if there was not much pain, they didn't notice other possible indicators, like a change in stool size or stool habits, etc.

This cancer isn't like ovarian or pancreatic, that produce vague symptoms that aren't fully identified until too late. I just think people ignore the signs or don't know what they mean. Also, a CBC would generally not catch colon cancer.