A comparison of conventional cytology, DNA ploidy analysis, and fluorescence in situ hybridization for the detection of dysplasia and adenocarcinoma in patients with Barrett's esophagus

Abstract

New detection methods with prognostic power are needed for early identification of dysplasia and esophageal adenocarcinoma (EA) in patients with Barrett's esophagus (BE). This study assessed the relative sensitivity and specificity of conventional cytology, DNA ploidy analysis with digital image analysis (DIA), and fluorescence in situ hybridization (FISH) for the detection of dysplasia and adenocarcinoma in endoscopic brushing specimens from 92 patients undergoing endoscopic surveillance for BE. FISH used probes to 8q24 (C-MYC), 9p21 (P16), 17q12 (HER2), and 20q13. Four-quadrant biopsies taken every centimeter throughout visible Barrett's mucosa were used as the gold standard. The sensitivity of cytology, DIA, and FISH for low-grade dysplasia was 5%, 5%, and 50%, respectively; for high-grade dysplasia (HGD), 32%, 45%, and 82%, respectively; and for EA, 45%, 45%, and 100%, respectively. FISH was more sensitive (P < .05) than cytology and DIA for low-grade dysplasia, HGD, and EA. The specificity of cytology, DIA, and FISH among patients (n = 14) with tissue showing only benign squamous mucosa was 93%, 86%, and 100% (P = .22), respectively. All patients with a polysomic FISH result had HGD and/or EA within 6 months (n = 33). There was a significant difference between FISH categories (negative, 9p21 loss, gain of a single locus, and polysomy) for progression to HGD/EA (P < .001). These findings suggest that FISH has high sensitivity for the detection of dysplasia and EA in BE patients, with the power to stratify patients by FISH abnormality for progression to HGD/EA. Additional studies are needed to further evaluate the clinical use of FISH.

Fig. 1

Example of (A) diploid (negative) and (B) aneuploid (positive) DIA histograms. DNA content (x-axis) is plotted against the number of cells (y-axis). The DNA content of diploid cells is within the 2c range (DNA index = 0.95-1.10); tetraploid cells, within the 4c range (DNA index = 1.90-2.10); and aneuploid cells, between 2c and 4c or >4c (DNA index = 1.11-1.89; >2.10).

Fig. 2

Representative examples of FISH signal patterns: (A) normal (2 signals of each of the 4 probes), (B) homozygous 9p21 loss (no red signals), (C) polysomy (2 or more signals of 2 or more probes), (D) gain of 8q24 (>2 aqua signals). 9p21 (red), 17q12 (green), 8q24 (aqua), and 20q (gold).

Fig. 3

Sensitivity and specificity of cytology using different interpretation cutoffs. “Cytology P”: only positive interpretations considered positive for dysplasia or EA; “Cytology P + S”: positive and suspicious interpretations considered positive for dysplasia or EA; “Cytology P + S + A”: positive, suspicious, and atypical cytologic interpretations considered positive for dysplasia or EA. Specificity is calculated by considering patients with benign squamous mucosa.

Fig. 4

A, Sensitivity of cytology, DIA, and FISH for the detection of LGD, HGD, and EA (cytology includes positive and suspicious interpretations). B, Specificity of cytology, DIA, and FISH when considering patients with benign squamous mucosa.

Fig. 5

The types of chromosomal abnormalities observed in brushing specimens among the FISH positive cases based upon the histologic result from the concurrent biopsy.

Fig. 6

Kaplan-Meier analysis demonstrates differences in time to HGD and/or EA for patients based upon the FISH abnormality found in initial brushing specimen (P < .001).