The oncogene ras p21 expression and DNA content in 46 cases of colorectal tumor were analysed quantitatively with flow cytometry and cyto-immunofluorescence staining technique. The results showed that the positive rate of ras p21 expression was 65.7% and the rate of DNA aneuploid was 74.3% in colorectal carcinomas. Ras p21 expression was higher in colorectal adenocarcinomas than that of the adenomas and normal mucosa. DNA ploid and proliferative index had some association with ras p21 expresssion. Detection of ras p21 expression and DNA content in tumors may be helpful in predicting the outcome of colorectal cancer patients.
