Determining the telomerase activity of exfoliated cells in intestinal lavage solution to detect colorectal carcinoma

In order to make a definitive diagnosis of colorectal carcinoma, it is desirable to detect cancerous cells in stool samples. The detection of cancer gene products in stool samples, however, is said to be extremely difficult. The involvement of telomerase in the development of various malignancies has been reported. We therefore performed colonoscopy and thereby collected the intestinal lavage solution remaining in the lower portion of rectum to determine any possible signs of colorectal carcinoma. This fluid consisted of a combination of stool and exfoliated intestinal mucosa. We examined the telomerase activity of the intestinal lavage solution, collected from 19 colorectal carcinoma patients and from 11 volunteers (colonospically normal controls) based on the method of the telomeric repeat amplification protocol (TRAP) assay. All patients drank a polyethylene glycol-electrolyte lavage solution (PEG-ELS) before the examination. Sample solutions were collected by the colonoscope at the beginning of colonoscopy. Telomerase activity was thus found in 11 (57.9%) of the 19 intestinal lavage solution samples. In contrast, all eleven samples from the colonoscopically normal subjects were negative. These findings thus suggest that measuring telomerase activity of exfoliated cells in intestinal lavage solution may thus be useful as a new diagnostic method for colorectal carcinoma.