Aberrant crypt foci in human colon carcinogenesis.

We developed a procedure for the endoscopic visualization in humans of aberrant crypt foci (ACF), preneoplastic lesions of the colon mucosa, and we determined the frequency of ACF in resected sections of human colon. For the endoscopy we studied 12 consenting adults (6 controls and 6 colon cancer cases) by dyeing colon mucosa with 0.5% methylene blue and searching ACF with a magnifying endoscope. ACF of varying dimensions were visualized in all subjects. We also studied colon surgical specimens from patients with colon cancer or diverticulitis. After staining the mucosa with 2% methylene blue, we found approximately the same density of ACF in the colon mucosa of the patients with colon cancer as in that of patients with diverticulitis (ACF/cm2 were 0.124 +/- 0.143 [N = 14] and 0.108 +/- 0.210 [N = 4], respectively [mean +/- SD]). In conclusion, the visualization of ACF with methylene blue in humans does not identify groups at low and high risk of colon cancer.