How likely is it that a 24 year old like myself would have colon, esophageal, or stomach cancer due to gerd- acid reflux?

Unlikely if treated: Gerd s itself will not give esophageal or stomach cancer , but constant acid reflex injury changes the mucosa of lower esophagus, called barrets ulcer a metaplasia which has higher incidence of malignant transformation, gerds has no roll in colon cancer so at the age of 24 you do not have to worry , put your life to best use and enjoy it.

Not but: It's not likely but it is possible. Why are you thinking of these? Need more info to be able to help you. Definitely see a doctor.