Allelic imbalance of 7q32.3-q36.1 during tumorigenesis in Barrett's esophagus.

Malignant transformation of Barrett's esophagus is characterized by three distinct premalignant stages: intestinal metaplasia (MET), low- (LGD), and high-grade dysplasia (HGD). We reported recently an increase in the frequency of loss of 7q33-q35 between LGD and HGD as determined by comparative genomic hybridization (P. H. J. Riegman et al., Cancer Res., 61: 3164-3170, 2001). Now the 7q32.3-q36.1 region was additionally characterized by allelotype analysis with 11 polymorphic markers in 15 METs, 20 LGDs, 20 HGDs, and 20 Barrett's adenocarcinomas from different patients. Low percentages of imbalance were determined in METs and LGDs, 7% and 10%, respectively, whereas HGDs and Barrett's adenocarcinomas revealed high percentages of loss, 75% and 65%, respectively. This difference in frequency between LGDs and HGDs appeared highly significant: P = 0.00007. The majority of imbalances were found at D7S2439 and D7S483, located on 7q36.1. These data suggest that markers from this area can be used as a diagnostic tool in Barrett's esophagus, i.e., to distinguish between watchful waiting and active treatment.