You have to be between the ages of 40- 79 (?) and must not have had a colonoscopy in the last 12 months I believe? You also can't have any medical conditions that need a doctor's attention while on the trip, I think it said.
Go to cbscares.com for entering and to read the rules.
Who knows, if you don't mind the publicity that might be required, this could be a good opportunity to discuss our issue if one of us were to win!
Joan