Aberrant TP53 detected by combining immunohistochemistry and DNA‐FISH improves Barrett's esophagus progression prediction: A prospective follow‐up study

Abstract

Barrett's esophagus (BE) goes through a sequence of low grade dysplasia (LGD) and high grade dysplasia (HGD) to esophageal adenocarcinoma (EAC). The current gold standard for BE outcome prediction, histopathological staging, can be unreliable. TP53 abnormalities may serve as prognostic biomarkers. TP53 protein accumulation detected by immunohistochemistry (IHC) indirectly assesses TP53 mutations. DNA fluorescent in situ hybridization (FISH) on brush cytology specimens directly evaluates gene locus loss. We evaluated if IHC and FISH are complementary tools to assess TP53 abnormalities and tested their prognostic value in a long-term prospective follow-up of a BE cohort. TP53 IHC on tissue sections and FISH on brush cytology specimens were evaluated for 116 BE patients with respect to the different histological stages. The TP53 abnormalities were further studied in a panel of cell lines representative of the Barrett's carcinogenic sequence. For 91patients, the predictive value of TP53 abnormalities with respect to progression to HGD/EAC was tested after long term follow-up. The frequency of IHC and FISH TP53 abnormalities increased significantly with increasing histological stage (P < 0.001, Chi(2) -test). Combining the techniques detected TP53 abnormalities in 100% of patients with LGD, HGD, and EAC. Multivariate analysis showed that IHC (hazard ratio: 17, 95% CI: 3.2-96, P = 0.001) and FISH (hazard ratio: 7.3, 95% CI: 1.3-41, P = 0.02) were both independent significant predictors of progression. Combining FISH and IHC in assessing TP53 abnormalities leads to an increased detection rate of TP53 aberrations and improved accuracy for predicting BE progression.

Dynamic clonal equilibrium and predetermined cancer risk in Barrett’s oesophagus

“…Surprisingly, the size of the biggest clone, evidenced by p53 loss and/or p53 relative locus loss was not a prognostic marker. Thus, in this cohort of BE patients with no dysplasia, p53 loss did not bear prognostic potential, which is in contrast to findings in Barrett cohorts that also included patients with low- and high-grade dysplasia16202122. We included the significant prognostic markers in a multivariate model with age and circumferential Barrett's length (accepted prognostic factors232425) and found that all eight genetic variables were the most significant predictors of progression (Supplementary Table 4).…”

“…3). In contrast, p53 loss observed in at least 5% of the cells was found in only 7.5% of patients ( n =24), and relative p53 locus loss16 (defined by copy-loss or fewer copies of the p53 locus relative to the chr17 centromere (Methods)—observed in more than 5% of cells was seen in 10.6% of patients ( n =34). In addition, comparison of the data from multiple brushes collected at the same endoscopy (termed repeat brushes) validated the reproducibility of our FISH analysis (Methods and Supplementary Fig.…”

Derivation of genetic biomarkers for cancer risk stratification in Barrett’s oesophagus: a prospective cohort study

“…The FISH analysis as performed in this study may have underestimated p53 losses, since p53 locus loss may also occur in cells with genetic instability and gains for chromosome 17, which could lead to ‘copy neutral loss of heterozygosity’. [30,31] Also, point mutations leading to abnormal p53 function were undetectable by our methods. Other discrepancies might be due to differences in detection methods.…”

Radiofrequency Ablation Is Associated With Decreased Neoplastic Progression in Patients With Barrett's Esophagus and Confirmed Low-Grade Dysplasia

“…A more precise clinical test would be p53 fluorescent in situ hybridization which is less widely available and has increased cost. 39 Other commonly involved genes in Barrett’s esophagus include p16 abnormalities as well as evidence of chromosomal instability both of which could be assessed with immunohistochemistry and FISH respectively. These tests may better stratify risk of progression though data supporting their use to date are limited.…”