Association of ABCG2 Polymorphisms on Triple Negative Breast Cancer (TNBC) Susceptibility Risk.

Objective: The aim of this study was to elucidate the association of ATP-binding cassette super-family G member 2 (ABCG2) gene polymorphisms with individual susceptibility to Triple Negative Breast Cancer (TNBC) as well as clinicopathological variables in TNBC patients. Two common polymorphisms in Asian population, ABCG2 34 G>A and 421 C>A was selected in this study.

Methods: Blood samples were collected from 75 TNBC patients and 83 controls. Genomic DNA was extracted from blood samples and the SNP genotyping was performed by using PCR-RFLP technique. The genotypes were characterized and grouped into homozygous wildtype, heterozygote and homozygous variant based on the band size. The result was subjected to statistical analysis.

Results: The A allele and AA genotype of ABCG2 421 C>A had OR of 3.011 (p=0.003, 95% CI: 1.417-6.398) and 9.042 (p=0.011, 95% CI: 1.640-49.837), to develop advanced staging carcinoma respectively. The AA genotype of ABCG2 421 C>A polymorphism was also associated with metaplastic and medullary carcinoma with an OR of 6.429 (p=0.018, 95% CI: 1.373-30.109). A significant association was also found in haplotype 34G/421A of ABCG2 with advanced cancer staging as well as metaplastic and medullary carcinoma with OR of 2.347 (p=0.032, 95% CI: 1.010-5.560) and 2.546 (p=0.008, 95% CI: 1.005-6.447), respectively.  Conclusion: The present study suggests that ABCG2 421 C>A polymorphism was associated with metaplastic and medullary histology and advanced cancer staging in TNBC patients.