Reappraisal of K-ras and p53 gene mutations in the recurrence of Dukes' B2rectal cancer after curative resection

BACKGROUND/AIMS: Recurrence of rectal cancer remains a major clinical probl em. This study was conducted to evaluate the impact of K-ras and p53 mutati ons on the recurrence of rectal cancer. METHODOLOGY: A total of 166 resected Dukes' B2 stage rectal carcinomas were collected between January 1990 and April 1994. The stored frozen tissues w ere retrieved for immunocytochemistry of p53 and genomic analysis of K-ras and p53 genes. The data of K-ras and p53 gene mutations were correlated wit h clinicopathological variables. The concordance of immunocytochemistry wit h genomic analysis in the survey of p53-mutations was examined. The follow- up data were analyzed by Kaplan-Meier estimator. RESULTS: Sixty-nine patients (41.6%) developed recurrent tumor. A significa ntly higher recurrence rate (p=0.0013) and shorter median recurrence time w ere noted in p53 mutated than non-mutated cancers. Mutations in K-ras gene do not significantly increase the risk of tumor recurrence (p=0.1702), K-ra s and p53 mutations are not associated with clinicopathological parameters (p>0.05). Kappa statistic indicates highly significant reproducibility betw een immunocytochemistry and genomic analysis for p53 mutations (p<0.0001). CONCLUSIONS: Presence of p53 mutation significantly increases the recurrenc e rate and shortens the recurrence-time of the resected rectal cancers. Pre -operative routine check for p53 mutations by immunocytochemistry may be be neficial in choosing the optimal surgical strategy for rectal cancer.