LAUSR

BACKGROUND Esophageal adenocarcinoma (EAC) is the sixth leading cause of cancer-related death worldwide. It develops through Barrett's metaplasia - dysplasia sequence. However, the effectiveness of endoscopic surveillance is limited, since diagnosis of low-grade dysplasia (LGD) is known to be challenging for pathologists. Our aim was to compare the risk of Barrett's progression based on diagnoses of general and expert gastrointestinal (GI) pathologists in a population-based cohort. METHODS A total of 60 patients with non-dysplastic metaplasia (BE) or LGD progressing to high grade dysplasia (HGD) or EAC during follow-up could be identified in the population. For comparison, series representing non-progressive BE (n = 56) and LGD cases (n = 54), matched for age, gender, and length of follow-up were collected. All available original HE stained slides (n = 292) were blindly re-evaluated by two experienced GI pathologists and patient groups of progressive non-progressive BE and LGD were formed according to revised diagnoses. RESULTS Original diagnosis for each sample was changed in 25% of BE, 59% of LGD, and 33% of HGD diagnoses. Of the original LGD diagnoses, 53% were downgraded to BE or indefinite for dysplasia (ID). Of LGD diagnoses made by an expert GI pathologist, 61% were in the progressive LGD group, whereas only 42% of general pathologists' LGD diagnoses were in the progressive LGD group. CONCLUSION Based on this retrospective case-control study, LGD is strongly over-diagnosed among general pathologists. LGD diagnosed by expert GI pathologists predicts progressive disease. Recommendation for consensus diagnosis by expert GI pathologists is justified also in the Finnish population-based setting.