Single nucleotide polymorphisms in nucleotide excision repair genes XPA, XPD, XPG and ERCC1 in advanced colorectal cancer patients treated with first-line oxaliplatin/fluoropyrimidine.

BACKGROUND/AIMS: Oxaliplatin damages the DNA, leading to apoptosis. XPA, XPD, ERCC1 and XPG genes are involved in DNA repair, and single nucleotide polymorphisms (SNPs) in these genes can influence the efficacy of oxaliplatin. We examined SNPs in these genes and correlated the results with time to progression (TTP), overall survival and response to oxaliplatin in 42 advanced colorectal cancer patients (CRC) treated with first-line oxaliplatin/fluoropyrimidine.

METHODS: DNA was obtained from peripheral blood cells, and the allelic discrimination assay was used to analyze the XPA 5'UTR T/C, XPD Lys751Gln, ERCC1 Lys259Thr and XPG, C/T.

RESULTS: Patients with XPG C/C genotype had a longer survival (p = 0.001) and TTP (p = 0.009) than patients with XPG C/T or T/T genotypes, and patients with both XPG C/C and XPA T/C or C/C genotypes had a longer survival (p = 0.0001) and TTP (p = 0.0001) than patients with other genotypes. XPG (CC) combined with XPA (TC/CC) genotypes showed an independent role for TTP (relative risk, RR = 6.38; p = 0.0001) and survival (RR = 34; p = 0.0005).

CONCLUSION: Polymorphism in XPG combined with XPA may be an important prognosticator of clinical outcome following oxaliplatin/ fluoropyrimidine chemotherapy. Further studies in larger patient cohorts are warranted to confirm their role in CRC.