A 52-year-old woman with a long history of chronic gastroesophageal reflux disease (GERD) and Barrett's esophagus undergoes endoscopy with multiple biopsies. Histology shows replacement of the normal stratified squamous epithelium of the distal esophagus with columnar epithelium containing goblet cells (intestinal-type metaplasia). In an adjacent area, the columnar epithelium shows increased nuclear-to-cytoplasmic ratio, loss of nuclear polarity, and crowded nuclei, but the basement membrane remains intact. The patient is counseled about surveillance. Which of the following best explains why this patient requires close endoscopic follow-up despite the reversibility of metaplasia?