Clinical significance of ras p21 overexpression for patients with an advanced colorectal cancer.

The expression of ras oncogene product p21 was examined in 45 paraffin-embedded sections of primary advanced colorectal cancers, using the anti-v-H-ras p21 monoclonal antibody Y13-259. Fourteen of these specimens (31 percent) were stained positively. The incidence of lymphatic vessel invasion of cancer cells and lymph node metastasis correlated statistically with the overexpression of ras p21. The depth of invasion and incidence of liver metastasis in the p21-positive group were more prominent than in the p21-negative group. Statistically significant differences were evident in operative curability and clinical stage at initial surgery and in the long-term survival rate between these groups (P less than 0.05). We propose that ras p21 overexpression may serve as a marker to predict the prognosis of colorectal cancer.