Reappraisal of K-ras and p53 gene mutations in the recurrence of Dukes' B2 rectal cancer after curative resection.

BACKGROUND/AIMS: Recurrence of rectal cancer remains a major clinical problem. This study was conducted to evaluate the impact of K-ras and p53 mutations 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 were 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 with clinicopathological variables. The concordance of immunocytochemistry with 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 significantly higher recurrence rate (p = 0.0013) and shorter median recurrence time were 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-ras and p53 mutations are not associated with clinicopathological parameters (p > 0.05). Kappa statistic indicates highly significant reproducibility between immunocytochemistry and genomic analysis for p53 mutations (p < 0.0001).

CONCLUSIONS

Presence of p53 mutation significantly increases the recurrence rate and shortens the recurrence time of the resected rectal cancers. Pre-operative routine check for p53 mutations by immunocytochemistry may be beneficial in choosing the optimal surgical strategy for rectal cancer.