Abnormal DNA ploidy and proliferative patterns in superficial colonic epithelium adjacent to colorectal cancer.

Superficial colonic cells were taken from normal-appearing mucosa at 2, 5, and 10 cm proximal and distal to colorectal cancer margins in 37 patients. The DNA ploidy and proliferative pattern of each sample were determined using flow cytometry. In 11 patients, histology of mucosal sections from the same sites also was analyzed. We found a higher frequency of aneuploidy than previously reported in mucosa up to 10 cm from a colorectal cancer; 62% (23/37) of the primary cancers were aneuploid, and of these, 48% (11/23) were associated with adjacent aneuploid mucosa. The mucosa adjacent to the 14 diploid cancers had only diploid characteristics. The proliferative activity (as reflected by synthetic (S) phase fraction) of aneuploid cancers (21.1 +/- 2.0% SEM) and aneuploid mucosa as far as 10 cm away (21.2 +/- 2.1% SEM) was higher than in normal controls (10.2 +/- 0.7% SEM) (P less than 0.0005). Parallel cytology excluded shed cancer cells as an explanation for these findings. Histology showed diffuse, generally mild and reactive, mucosal abnormalities in eight of 11 patients. Ploidy did not correlate with histologic abnormalities. The findings of aneuploidy and high S-phase fraction in uninvolved superficial mucosa provide evidence for a field defect in mucosa adjacent to colorectal cancer and support the concept that the large bowel mucosa behaves as a unit in carcinogenesis.