Clinical-pathological correlation of K-Ras mutation and ERK phosphorylation in colorectal cancer.

The Ras-ERK pathway is frequently up-regulated in colorectal cancer. We analyzed the clinical-pathological correlation of K-Ras mutation and phospho-ERK expression in colorectal cancer. K-Ras mutations were detected in only 32.5% (41/126) of the colorectal cancer cases, while all cancers were positive for phospho-ERK staining. Colorectal cancer with wild-typeK-Ras and low phospho-ERK expression had a significantly higher survival rate (log-rank P = 0.04). There were 9 cases of K-Ras mutation/low phospho-ERK diseases; 88.9% (8/9) of them were stage III/IV diseases. High phospho-ERK expression was associated with a high stage and T status of the cancer, yet combined K-Ras mutation/phospho-ERK expression analysis further increased the efficiency of colorectal cancer prognosis. Our results demonstrate that Ras-ERK pathway correlated closely with colorectal cancer progression. Moreover, although colorectal cancer with K-Ras mutations has a more aggressive phenotype; the mutation rate is not very high. Phospho-ERK may be a useful marker in combination with K-Ras for improving the prognosis of colorectal cancer.