Endoscopic determination of the aberrant crypt foci density by magnification chromoscopy: Colorectal cancer vs. Benign diseases of colon

Introduction: Aberrant crypt foci (ACF) are microscopic foci of enlarged and elevated crypts. Limited animal studies suggest that these lesions are precancerous. However, there is uncertainty if their density is higher in colorectal cancer in humans and if they can be evaluated and enumerated endoscopically. Aim: To determine the ACF density by magnification chromoscopy (MC) and to compare it to the value obtained by dissecting microscopy (DM) in patients with colorectal cancer and benign diseases of colon in an ex vivo model. Methods: Surgical specimens from 18 subjects (14 cancer, 4 benign) were studied. The colonic mucosa was stained with 0.2% methylene blue after washing with 10% acetylcysteine. Each specimen was then cut into 4 cm² segments and examined with the Olympus CF-200Z magnifying colonoscope at a distance of 2-3 mm (magnification 30X-40X). The muscularis propria of the methylene blue stained tissue was subsequently discarded before examination by dissecting light microscopy by another investigator. The ACF density was calculated by dividing the number of ACF by the surface area examined. Statistical analysis was performed by the t-Test for unpaired samples. Results: The total areas examined were 626 cm² in the cancer and 216 cm² in the benign group. The average ages of the patients with cancer and benign diseases were 71.9 (range 51-53, median 73; 6 male) and 64.5 (range 37-77, median 72; all male) years, respectively. The ACF density was higher in the cancer group both by magnification chromoscopy and dissecting microscopy. This difference, however, reached statistical significance only when the specimens were evaluated by magnification chromoscopy. ACF Density (X±SEM. Range) MC (#/cm²) DM (#/cm²) Cancer (n= 14) 0.19±0.04(0-0.52) 0.16±0.05 (0-0.75) Benign (n=4) 0.05±0.01(0.04-.07) 0.04±0.02 (0-0.09) P value, one-tail 0.04 0.12 Summary: The ACF density can be determined by MC ex vivo. Subjects with colorectal cancer appear to have higher ACF densities compared to patients with benign diseases. Conclusion: Magnification chromoscopy can detect ACF ex vivo and may become a useful technique for estimating the ACF density in vivo. Given large variations in the ACF density values, however, large groups of subjects need to be evaluated to determine if the density is significantly higher in patients with colorectal cancer compared to those with benign diseases.