Margriet R. Timmer

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

Barretts 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 Barretts 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, Chi2‐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.

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

Objective The risk of developing adenocarcinoma in non-dysplastic Barretts oesophagus is low and difficult to predict. Accurate tools for risk stratification are needed to increase the efficiency of surveillance. We aimed to develop a prediction model for progression using clinical variables and genetic markers. Methods In a prospective cohort of patients with non-dysplastic Barretts oesophagus, we evaluated six molecular markers: p16, p53, Her-2/neu, 20q, MYC and aneusomy by DNA fluorescence in situ hybridisation on brush cytology specimens. Primary study outcomes were the development of high-grade dysplasia or oesophageal adenocarcinoma. The most predictive clinical variables and markers were determined using Cox proportional-hazards models, receiver operating characteristic curves and a leave-one-out analysis. Results A total of 428 patients participated (345 men; median age 60 years) with a cumulative follow-up of 2019 patient-years (median 45 months per patient). Of these patients, 22 progressed; nine developed high-grade dysplasia and 13 oesophageal adenocarcinoma. The clinical variables, age and circumferential Barretts length, and the markers, p16 loss, MYC gain and aneusomy, were significantly associated with progression on univariate analysis. We defined an ‘Abnormal Marker Count’ that counted abnormalities in p16, MYC and aneusomy, which significantly improved risk prediction beyond using just age and Barretts length. In multivariate analysis, these three factors identified a high-risk group with an 8.7-fold (95% CI 2.6 to 29.8) increased HR when compared with the low-risk group, with an area under the curve of 0.76 (95% CI 0.66 to 0.86). Conclusions A prediction model based on age, Barretts length and the markers p16, MYC and aneusomy determines progression risk in non-dysplastic Barretts oesophagus.

Genetic Abnormalities in Biliary Brush Samples for Distinguishing Cholangiocarcinoma from Benign Strictures in Primary Sclerosing Cholangitis

Background. Primary sclerosing cholangitis (PSC) is a chronic inflammatory liver disease and is strongly associated with cholangiocarcinoma (CCA). The lack of efficient diagnostic methods for CCA is a major problem. Testing for genetic abnormalities may increase the diagnostic value of cytology. Methods. We assessed genetic abnormalities for CDKN2A, TP53, ERBB2, 20q, MYC, and chromosomes 7 and 17 and measures of genetic clonal diversity in brush samples from 29 PSC patients with benign biliary strictures and 12 patients with sporadic CCA or PSC-associated CCA. Diagnostic performance of cytology alone and in combination with genetic markers was evaluated by sensitivity, specificity, and area under the curve analysis. Results. The presence of MYC gain and CDKN2A loss as well as a higher clonal diversity was significantly associated with malignancy. MYC gain increased the sensitivity of cytology from 50% to 83%. However, the specificity decreased from 97% to 76%. The diagnostic accuracy of the best performing measures of clonal diversity was similar to the combination of cytology and MYC. Adding CDKN2A loss to the panel had no additional benefit. Conclusion. Evaluation of MYC abnormalities and measures of clonal diversity in brush cytology specimens may be of clinical value in distinguishing CCA from benign biliary strictures in PSC.

Mo1923 Non-Dysplastic Barrett's Esophagus Is Not Created the Same: Genetic Abnormalities in Non-Dysplastic Barrett's Esophagus Are Dependent on Clinical Context

academic based practices. 90% required intestinal metaplasia for the diagnosis of Barretts esophagus. Only 67% were aware of the Prague classification, which was used by 53% of those aware of it. The annual risk of progression to esophageal adenocarcinoma was reported as 0.1-0.5% by 76% of respondents, but was reported as . 5% per year by 14%. Screening practices were highly variable, with 35% screening all patients with chronic GERD symptoms regardless of gender or age, 27% reserving screening for age . 50yrs, and 31% screening those with multiple risk factors associated with Barretts esophagus. 85% of respondents did not offer repeat screening after an initial negative EGD whereas repeated screening for Barretts after a negative examination was performed by 10% after 3-5 years. 14% performed biopsies of a normal appearing Z-line. Surveillance for non-dysplastic Barretts was performed at 3-5 year intervals by 79%. Electronic chromoendoscopy was the only widely used advanced imaging modality, reported by 60%, whereas , 1% used confocal endomicroscopy. Four quadrant biopsies at 2 cm intervals were done by 77% for non-dysplastic Barretts and at 1 cm intervals by 76% for dysplastic Barretts. Histopathological confirmation of dysplasia was reported by 86%. See Table for additional details. Conclusions: Among respondents, we observed that there is excellent adherence to the new AGA Barretts esophagus guidelines in general, particularly in the areas of diagnosis and cancer risk estimates, but there are some notable exceptions. Considerable variability exists in terms of 1) identifying risk factors for screening, 2) timing of surveillance intervals, and 3) use of the Prague classification. Reasons underlying the continued variability in adherence to Barretts practice guidelines merit further study. Table 1. Diagnostic, screening, and surveillance practices