ERCC1, XRCC1 and GSTP1 Single Nucleotide Polymorphisms and Survival of Patients with Colon Cancer Receiving Oxaliplatin-Based Adjuvant Chemotherapy

Background: While single nucleotide polymorphisms (SNP) in genes involved in DNA repair or drug metabolism have been shown to influence survival of metastatic colon cancer patients treated with FOLFOX, data on adjuvant setting are scarce. Methods: This study evaluated the correlation between disease-free survival (DFS) of 210 unselected stage III colon cancer patients receiving FOLFOX chemotherapy, and ERCC1-118 (rs11615, c.354T>C), XRCC1-399 (rs25487, c.1196G>A) and GSTP1-105 (rs1695, c.313A>G) polymorphisms. SNP were determined on tumor DNA using a PCR-based RFLP technique. Results: In univariate analysis, a trend towards longer DFS was observed for ERCC1 (C/T + T/T) versus (C/C) (HR=2.29; p=0.06), and XRCC1 (A/A) versus (G/G + G/A) (HR=1.61; p=0.16), but not for GSTP1 genotypes; a statistically significant p value was obtained when combining ERCC1 and XRCC1 favorable genotypes (0 versus ≥ 1 favorable genotypes, HR=2.42; p=0.02). After adjustment on tumor stage, lymph node ratio and differentiation grade, multivariate analysis showed that combining ERCC1 and XRCC1 genotypes gave a p value slightly above the threshold for statistical significance (HR=2.03; p=0.06), which was lower than for tumor stage, lymph node ratio or differentiation grade. Conclusion: The association of ERCC1 and XRCC1 polymorphisms may influence the prognosis of stage III colon cancer patients treated with FOLFOX adjuvant chemotherapy. Yet, these findings need to be confirmed in independent prospective studies.