Assessment of genetic damage in inflammatory, precancerous, and cancerous pathologies of the esophagus using the comet assay.

The last few decades of cancer research indicate that DNA damage is a prerequisite for development of malignancies. An increase in damage points to reduced repair capacity and risk for progression. We have used the comet assay to assess DNA damage in individuals with various disorders of the upper gastrointestinal (GI) tract in a cohort of patients from South India. After thorough clinical, endoscopic, and histopathological evaluation, patients were categorized into cancers, precancers, inflammatory pathologies, and controls. Results from the comet assay performed on esophageal tissue cells and blood from the same patients showed good correlation of damage in the paired samples; subsequent assays were performed in blood. There was more DNA damage in cancers when compared with controls. A significant increase in damage in cancers (37%) and precancers (30.7%) when compared with the inflammatory pathologies (15.6%) and controls (10.03%) was noted. The interindividual variation observed was independent of confounding factors such as tobacco and alcohol. We suggest that the damage seen in the esophageal tissue is likely to be disease-related, whereas that seen in blood may be a reflection of disease. Individuals with greater damage may be prone to disease progression and the comet assay can be used as a cost-effective biomonitoring tool to assess damage and identify these individuals at risk for a progressive pathology, even to malignancy.