PATHOGENETIC IMPLICATIONS OF DNA NONDIPLOIDY IN COLORECTAL CANCERS

PURPOSE: Several studies propose that proximal and distal colorectal c ancers have a different pathogenesis, We tested the hypothesis: using flow cytometric DNA analysis. METHODS: DNA analysis was performed in 7 19 patients with colorectal cancer. In addition, histopathologic data were re-evaluated in a blinded fashion by a single pathologist. RESULT S: Distal tumors were more often nondiploid than were proximal tumors (61 vs. 43 percent; P = 0.015). Compared with the proximal tumor, dist al tumors were smaller (P = 0.0001) and had less desmoplastic reaction (39 vs. 53 percent; P = 0.0001). Tumor location had no significant as sociations with the remaining parameters, including mucin production, perineural invasion, blood/lymphatic vessel invasion, lymphocytic infi ltration, histologic grade, tumor stage, gross appearance, age, and ge nder. CONCLUSIONS: The unequal distribution of ploidy suggests distinc t pathogenetic mechanisms at proximal and distal sites.