PLEASE, NOT ANOTHER MARKER OF CANCER RISK IN BARRETT'S ESOPHAGUS!

These authors investigated cellular proliferation of the different histological subtypes (fundic, junctional, and specialized) of Barrett's esophagus. They hypothesized that the observation that cancer seems to arise exclusively in patients with specialized type epithelium may be explained if this histological subtype had increased cell‐proliferation. Accelerated proliferation would increase the likelihood of mutation and or genomic instability resulting in carcinogenesis in some of these patients. Proliferating cell nuclear antigen (PCNA) is a nuclear protein thought to be a cell cycle regulator, thereby controlling proliferation. Antibodies to PCNA can be used to recognize (stain) PCNA on fixed tissues. These investigators used PC10 (a murine monoclonal antibody to PCNA) as a marker of cellular proliferation. Nuclear staining was a requirement, and three “zones” (luminal, crypts, and glands) were assessed for staining. Ninety‐three specimens from 45 patients were studied. Luminal staining occurred almost exclusively in the specialized Barrett's epithelium (mean score of 1.2) versus junctional type epithelium (mean score of 0.23) and fundic type epithelium (mean score of 0.04) (p= < 0.0001). Crypt and gland PCNA labeling scores were significantly greater in specialized epithelium versus the fundic or junctional type (p= < 0.0001). These authors concluded that PCNA immunolocalization reveals that a high proportion of specialized epithelial cells are proliferating (vs. fundic and junctional type), and there is an expansion of the proliferative compartment, observations that may explain the association between specialized epithelium and malignancy in Barrett's esophagus.