Just diagnosed with barrett esophagus after few mos of acid reflux. Does it mean precancerous?

By definition, but.. Barrett's esophagus is a response to chronic reflux; it can be short segment or long segment. Long segment is more associated with risk for malignancy. Barrett's is uncommon response to reflux; cancer is uncommon in barrett's. Barrett's pts get closer endoscopic scrutiny/surveillance. Can get rx re: reflux (it's unsure if it really decreases risk of ca), and to remove barrett's tissue before ca.