Not sure. Wikipedia wasnt clear on that point. But malignancy occurence is at .05% she did say she would have to get an endoscopy every two years.
That's the occurrence for her high-risk category? Is that annual or lifetime? If it's lifetime, I would say it's really in the category of "something to not bother worrying about" because that's a third of general female population's lifetime risk of, say, ovarian cancer.
Endoscopy every two years will be a PITA, but well worth it for early detection.
Ah, here, I looked it up and that's annual risk, but the good news is that it looks like the high mortality rate is usually due to late detection: http://digestive.niddk.nih.gov/ddiseases/pubs/barretts/
You probably don't need to stress about it too much... more of an inconvenience than anything else.