Significance of an exon 2 G4C14-to-A4T14 polymorphism in the p73 gene on survival in rectal cancer patients with or without preoperative radiotherapy.

BACKGROUND AND PURPOSE An exon 2 G4C14-->A4T14 polymorphism in the p73 gene was shown to be related to survival in several types of cancers, including colorectal cancer. The purpose was to investigate if this polymorphism was related to survival in rectal cancer patients with or without preoperative radiotherapy. MATERIALS AND METHODS DNA extracted from tissue of 138 rectal cancer patients that received preoperative radiotherapy or had surgery alone was typed for the polymorphism by PCR using confronting two-pair primers. RESULTS Among patients, 69% had GC/GC genotype, 27% had GC/AT and 4% had AT/AT. In the radiotherapy group, patients carrying the AT (GC/AT+AT/AT) allele had stronger expression of p53 (p=0.001) and survivin protein (p=0.03) than those carrying the GC/GC genotype. Further, among patients receiving preoperative radiotherapy the GC/GC genotype tended to be related to better survival (p=0.20). Patients with GC/GC genotype, along with negative p53 and weak survivin expression showed better survival than the other patients (p=0.03), even after adjusting for TNM stage and tumor differentiation (p=0.01, RR, 7.63, 95% CI, 1.50-38.74). In the non-radiotherapy group, the polymorphism was not related to survival (p=0.74). CONCLUSIONS Results suggest that the p73 G4C14-->A4T14 polymorphism could be one factor influencing outcome of preoperative radiotherapy in rectal cancer patients.