Investigation of prognostic value of polymorphisms within estrogen metabolizing genes in Lithuanian breast cancer patients

Background: Breast cancer is the most frequent oncological disease among women. Estrogens are known to play an important role in breast cancer development. Recognition of the relationship between polymorphisms within estrogen metabolizing genes and conventional prognostic factors of breast cancer might improve our knowledge on individualized breast cancer prognosis. Therefore, we aimed to investigate possible associations between germline genetic polymorphisms within GSTM1, GSTT1, GSTP1, SULT1A1 and UGT1A1 genes and breast cancer clinicopathological characteristics together with disease progression. Methods: Our study involved 80 young (younger than 50 years of age) breast cancer patients. PCR-based Restriction Fragment Length Polymorphism (RFLP) assay was used to determine GSTP1 and SULT1A1 genotypes. GSTM1 and GSTT1 null genotypes were detected by multiplex PCR. UGT1A1 polymorphism was investigated with microsatellite analysis. Relationships between genotypes and breast cancer clinicopathological features along with disease progression were estimated by Pearson's Chi-square test. Logistic regression analyses were performed to estimate the odds ratios associating different genotypes with clinicopathological characteristics and disease progression. Results: The study showed individuals with GSTT1 null genotype to have approximately 3.5 times higher risk for breast cancer progression than those with wild type genotype (OR = 3.472, 95% CI 1.043-11.559, P = 0.043). Moreover, SULT1A1 G638A AA genotype significantly increased the chances of HER2 molecular subtype breast cancer when compared to GG genotype (OR = 19.971, 95% CI 1.716-232.480, P = 0.017). Heterozygotes for GSTP1 A313G genotype were more likely to have positive lymph nodes in comparison to AA genotype carriers (OR = 2.803, 95% CI 1.049-7.487, P = 0.040). No significant correlation was determined for UGT1A1 A(TA) nTAA and GSTM1 +/- polymorphism alone or combined GTTT1 null and GSTM1 null genotype. Conclusions: Conclusively, our findings suggest that GSTT1 null genotype and SULT1A1 G638A AA genotype could be uselful genetic markers for breast cancer prognosis. Further analyses on larger sample size are required to highlight the effect of GSTP1 G allele on breast cancer prognosis.