K-ras gene mutation is a useful predictor of the survival of early stage colorectal cancers

Mutations in the K-ras gene were found to be of predictive value in the clinical outcome of non-small cell lung cancers, but its role in predicting the survival of colorectal cancer patients is still inconclusive. Point mutations in codon 12 or 13 of K-ras gene were analyzed in 64 colorectal cancers composing 4 Dukes' stage A, 34 stage B, 21 Stage C and 5 stage D. DNA extracted from the paraffin-embedded tissues of the 64 patients was a amplified with the polymerase chain reaction and subsequently analyzed by direct cycle sequencing. thirteen of sixty-four (20%) resected colorectal cancer specimens were found to have K-ras gene mutation and Dukes' stage were associated with the patients' survival. When stratified by Dukes' stage, the patients with mutated K-ras genes in the stratum of stage A or B were found to have shorter survival times than those without mutated K-ras genes (P = 0.003), but this was not the case in the stratum of stage C and D. The relative risk of mortality in the stratum of stage A or B was 7.74 (95% confidence interval: 1.72 - 34.89 by Cox regression analysis. We thereby conclude the K-ras gene mutation is a useful predictor of the survival of early stage colorectal cancers.