The C/A polymorphism in intron 11 of the XPC gene plays a crucial role in the modulation of an individual’s susceptibility to sporadic colorectal cancer

Background: Epidemiological data show that colorectal cancer (CRC) is the second most frequent malignancy worldwide. The involvement of “minor impact genes” such as XME and DNA-repair genes in the etiology of sporadic cancer has been postulated by other authors. Aim: we focused on analyzing polymorphisms in DNA-repair genes in CRC. We considered the following genes involved in DNA-repair pathways: base excision repair (OGG1 Ser326Cys, XRCC1 Trp194Arg and Arg399Gln); nucleotide excision repair [XPA (- 4)G/A, XPC C/A (i11) and A33512C (Lys939Gln), XPD Asp312Asn and A18911C (Lys751Gln), XPF Arg415Gln, XPG Asp1104His, ERCC1 C118T]; homologous recombination repair [ NBS1 Glu185Gln, Rad51 135G/C, XRCC3 C18067 (Thr241Met)]. Material and methods: The study group consisted of 133 patients diagnosed with sporadic CRC, while the control group was composed of 100 age-matched non-cancer volunteers. Genotyping was performed by PCR and PCR-RFLP. Fisher’s exact test with a Bonferroni correction for multiple testing was used. Results: We found that: i) XPC C/A (i11) heterozygous variant is associated with increased risk of CRC [OR is 2.07 (95% CI 1.1391,3.7782) p=0.038], ii) XPD A18911C (Lys751Gln) is associated with decreased risk of CRC [OR=0.4497, (95% CI 0.2215,0,9131) p=0.031] for an individual with at least one A allele at this locus. Conclusions: 1. the XPC C/A (i11) genotype is associated with an increased risk of sporadic colorectal cancer. 2. the NER pathway has been highlighted in our study, as a most important in modulation of individual susceptibility to sCRC.