Association of XPD Lys751Gln gene polymorphism with susceptibility and clinical outcome of colorectal cancer in Pakistani population: a case-control pharmacogenetic study

BACKGROUND

XPD Lys751Gln polymorphism may modulate inter-individual variation in repair capacity of DNA, which may enhance a person's susceptibility to develop colorectal cancer (CRC). The analysis of XPD Lys751Gln polymorphism may provide important information for identifying high-risk individuals and for selecting the most appropriate treatment for poor prognostic CRC patients.

OBJECTIVE

The overall objective was to find out the association of XPD Lys751Gln gene polymorphism with the risk of having a colorectal cancer and the ultimate clinical outcomes. In this study a total of 300 subjects (CRC and Controls), were genotyped for XPD Lys751Gln.

METHODS

Using PCR-RFLP methods, the association of XPD Lys751Gln gene polymorphism with the risk of having a colorectal cancer was studied. In addition to overall risk assessment, genotyping results were also investigated with respect to the lifestyle risk factors, patients treated with oxaliplatin-based chemotherapy and clinicopathological characteristics.

RESULTS

The overall correlation between the XPD Lys751Gln genetic variation and the CRC risk was observed to be significant with both the homozygous variant genotype Gln/Gln as well as heterozygous genotype Lys/Gln being associated with the increased risk of CRC. Additional stratified analyses revealed that XPD Lys751Gln variants remarkably increased risk of CRC in males and younger individuals (≤ 50 years), Naswar users (8.09-fold) and high intake of red meat.

CONCLUSIONS

Our findings suggest that the relationship between the XPD Lys751Gln variants and lifestyle factors modulates the risk for CRC in Pakistani population.

Lack of association between the XPD Lys751Gln polymorphism and colorectal cancer risk: a meta-analysis

Background

The xeroderma pigmentosum complementary group D (XPD) gene has been linked to the development of colorectal cancer (CRC) through disruption of DNA repair. Several studies have suggested that the XPD polymorphism Lys751Gln is associated with an increased risk of developing CRC. However, previous results remain inconclusive. Herein, we performed a meta-analysis to evaluate the potential for this relationship.

Methods

Relevant studies were retrieved from the PubMed database. Strict selection and exclusion criteria were determined, and the odds ratio with a 95% confidence interval was used to assess the strength of associations. The fixed or random effects model was selected on the basis of heterogeneity tests among studies. Publication bias was estimated using funnel plots and Egger’s regression test.

Results

The meta-analysis included 2,961 cases and 4,539 controls from eleven studies. The results indicated that the XPD Lys751Gln polymorphism had no association with CRC risk for all genetic models (Gln-Gln versus Lys-Lys, P=0.477; Lys-Gln versus Lys-Lys, P=0.283; Lys-Gln + Gln-Gln versus Lys-Lys, P=0.562), even when compared within subgroups based on ethnicity and source of controls.

Conclusion

Based on the results of our meta-analysis, there is no evidence of a link between the XPD Lys751Gln polymorphism and risk of CRC.