The alcohol dehydrogenase isoenzyme (ADH IV) as a candidate tumour marker of esophageal cancer

Abstract

Objective: Alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH) are present in esophageal cancer cells. Moreover the total activity of ADH as well as the activity of class IV ADH isoenzyme is significantly higher in cancer tissue than in healthy mucosa. The activity of these enzymes in cancer cells is reflected in the sera and could thus be helpful for diagnostics of esophageal cancer. The aim of this study was to investigate a potential significance of ADH isoenzymes and ALDH as tumour markers of esophageal cancer. We defined diagnostic sensitivity, specificity, predictive value for positive and negative results, and receiver-operating characteristics (ROC) curve for tested enzymes. Methods: Serum samples were taken for routine biochemical investigation from 180 patients with esophageal cancer before treatment. Total ADH activity was measured by a photometric method with p-nitrosodimethylaniline as a substrate and ALDH activity by a fluorometric method with 6-methoxy-2-naphtaldehyde as a substrate. For the measurement of the activity of class I and II isoenzymes we employed the fluorometric methods, with class-specific fluorogenic substrates. The activity of class III alcohol dehydrogenase was measured by a photometric method with formaldehyde and class IV with mnitrobenzaldehyde as a substrate. Results: There was a significant increase in the activity of class IV of ADH isoenzyme (7.65 mU/l vs 5.88 mU/l) and total ADH activity (1198 mU/l vs 848 mU/l) in the sera of esophageal cancer patients compared to the control. The diagnostic sensitivity for ADH IV was 72%, the specificity 76%, the positive and negative predictive values were 80% and 72% respectively. The area under the ROC curve for ADH IV was 0.65. Conclusion: The results suggest a potential significance of ADH IV as a marker of esophageal cancer.