[Flow cytometric DNA analysis of malignant potential in colorectal cancer]

Significance of flow cytometric DNA analysis for assessing malignant potential and survival of colorectal cancer was investigated using paraffin-embedded materials from 163 patients who underwent resection of curability A from 1971 to 1985, excluding intramucosal carcinoma. DNA diploid was confirmed in 46% (75 cases) of the patients and DNA aneuploid in 54% (88 cases). No significant correlation was seen between DNA ploidy and clinicopathological factors, such as tumor location, macroscopic type, histological type, depth of invasion, lymph node metastasis and stage. Cumulative survival rates after curable resection of colorectal cancer were significantly lower in patients with DNA aneuploid tumor than those with DNA diploid tumor. Furthermore, in patients in stage of II and III, survival rates were lower in DNA aneuploid patients than DNA diploid patients, respectively. A multivariate analysis of survival data using Cox's proportional hazard model showed that DNA ploidy was the significant discriminating factor on survival in stage II and III cancer. In conclusion, nuclear DNA ploidy in patients with stage II and III colorectal cancer undergoing curable resection may represent malignant potential and may be an independent prognostic factor.