Increased levels of luminol‐enhanced chemiluminescence by rectal mucosa of patients with colonic neoplasia: A possible marker for colonic neoplasia

Abstract

Increased colonic cell proliferation (CCP) has been reported in patients with colonic neoplasia. Previous studies in rats suggest that increased CCP is closely related to increased reactive oxygen metabolite (ROM) production. We hypothesized that, in humans, ROM production is also involved in increased CCP. Using a chemiluminescence probe, we estimated the levels of ROMs in the rectal mucosa of 37 patients who previously had colonic neoplasia (14 with cancer and 23 with polyps) and 20 control subjects who had normal colonoscopic examination and no history of colonic neoplasia. Normal‐appearing rectal mucosa of patients with colonic neoplasia contained significantly higher levels of luminol‐enhanced chemiluminescence (LECL) than rectal mucosa of control subjects (p < 0.01). There was no difference in LECL levels between patients with polyps and patients with cancer. Four of 20 controls and 31 of 37 patients had LECL levels 1,000 cpm/mg protein (positive and negative predictive values of 89% and 73%, respectively). Addition of indomethacin, a specific cyclooxygenase inhibitor, to the tissue suspension significantly decreased LECL levels. These preliminary data suggest that 1) ROMs may be involved in both the rate of CCP and the process of malignant cellular transformation, 2) oxidation of arachidonic acid via the cyclooxygenase pathway significantly contributes to the production of ROMs in rectal mucosa, and 3) measurement of the levels of LECL produced by the rectal mucosa may be a sensitive marker to screen for colonic neoplasia.