Flow cytometry analysis of cellular DNA content from formalin fixed paraffin embedded tissues: a useful technique in barrett’s surveillance?

Abstract

Demonstration of dysplasia on histology is the best current indicator of risk of developing cancer in Barrett's oesophagus. <h3>Aim</h3> To determine if cellular DNA determined by flow cytometry can be used in stratifying patients at greater risk of developing high grade dysplasia/adenocarcinoma (HGD/AC). <h3>Methods</h3> 165 oesophageal biopsies [40 no dysplasia, 50 indefinite for dysplasia (ID), 55 low grade dysplasia (LGD), 10 HGD and 10 AC) from 108 patients were analysed by flow cytometry using formalin fixed paraffin embedded tissue. <h3>Results</h3> Cellular DNA content showed a strong relationship with grade of histological dysplasia, with higher grades more likely to show abnormal ploidy (χ²=81.2, df=3, <i>p</i><0.0001). DNA analysis differentiated HGD/AC from no dysplasia, with only 5% (2/40) of biopsies showing no dysplasia having abnormal DNA cellular content compared to 100% (20/20) with HGD/AC (<i>p</i>≤0.0001). LGD was more likely to show abnormal ploidy (18%, 10/55) compared to no dysplasia (<i>p</i>=0.06), but ID (10% abnormal ploidy, 5/50) were similar to no dysplasia (<i>p</i>=0.38). Six patients with initially no dysplasia/ ID and diploid DNA developed HGD/AC over 2–7 years with concomitant development of aneuploidy. <h3>Conclusions</h3> Abnormal ploidy on flow cytometry is strongly associated with worsening dysplasia. However, HGD/AC can still develop in patients when initial biopsies show diploid DNA and no dysplasia.