RELATIONSHIP OF NUCLEAR-DNA CONTENT TO CLINICOPATHOLOGICAL FEATURES IN COLORECTAL-CANCER

Nuclear DNA content was determined in 123 colorectal adenocarcinomas b y flow cytometry using multiple frozen tumor samples. Thirty-three (26 .8%) carcinomas were classified as diploid and 90 as aneuploid (73.2%) . Presence of DNA aneuploidy was found to be unrelated to tumor stage and grade of differentiation and to other histopathological variables such as pattern of growth, degree of peritumoral lymphocytic infiltrat ion, and venous invasion. However, multiploid tumors (20/123, 16.3%) w ere more frequently noted in advanced stages of disease (Stages III an d IV, P < 0.025) and more often showed unfavorable histopathological f eatures, especially an infiltrating pattern of growth (P < 0.05), comp ared with diploid and single aneuploid carcinomas. Nuclear DNA content was found to be closely related to tumor site. Carcinomas of the prox imal (right and transverse) colon were more frequently diploid (19/43, 44.2% versus 14/80, 17.5% - P < 0.005) and more often displayed a DNA index (DI, defined as the ratio of the DNA content of neoplastic cell s to that of normal cells) less than or equal to 1.20 (27/43, 62.8% ve rsus 19/80, 23.7% - P < 0.001) than did tumors localized distally to t he splenic flexure. Nuclear DNA content was also found to be related t o tumor type. A high proportion of mucinous adenocarcinomas showed DI values less than or equal to 1.20 (14/21, 66.7%); conversely only 32 o f 102 (31.4%) non-mucinous adenocarcinomas had a DI less than or equal to 1.20 (P < 0.01). The nuclear DNA content of mucinous adenocarcinom as seemed to be independent of tumor location. These results seem to s uggest that the DNA ploidy pattern probably reflects different genetic mechanisms involved in the development of carcinomas in the proximal and distal colon. Furthermore, our data support the hypothesis that mu cinous adenocarcinoma represents a distinct clinicopathologic entity, possibly related to pathogenetic factors different from those acting i n the majority of non-mucinous adenocarcinomas.