Influence of glutathione transferase T1 and M1 gene polymorphisms on the effectiveness of chemotherapy in patients with breast cancer based on clinical and morphological characteristics

Relevance. The steady increase in the incidence of breast cancer (BC), as well as associated mortality and disability of the population, determines the relevance of the search for effective treatment and prevention of this pathology. Objective. Evaluation of differences in the effectiveness of chemotherapy for BC depending on the age, stage, and biological subtype of the tumor, considering the deletion status of the GSTT1 and GSTM1 genotypes in patients. Materials and methods. Data from 132 patients with BC who received chemotherapy treatment from 2013 to 2021 were analyzed. Polymorphic GSTM1 and GSTT1 variants were genotyped using multiplex polymerase chain reaction, followed by analysis of the melting curves of the reaction products. Results. The presence of the "null" genotype of GSTM1 and GSTT1 reduced the risk of relapse in patients with stage III disease by 0.52 times (95 % CI 0.29–0.89, p = 0.023) and 0.4 times, respectively (95 % CI 0.098–0.99, p = 0.049). Patients with luminal B HER2-positive breast cancer and GSTM1-0 had no fatalities. The risk of relapse was reduced in women with luminal B HER2-negative breast cancer subtype in the GSTM1-0 genotype group. In patients with luminal A, the overall survival (OS) with the GSTT1 wild type was 75.5 (±12.3) %, with GSTM1-0 there were no lethal outcomes (OR = 0.034, 95 % CI 0.02–0.045, p = 0.001), with luminal B HER2-negative subtypes, OS with the GSTT1 wild type was 69.9 (±8.5) % versus no lethal cases with the null genotype (OR = 0.035, 95 % CI 0.025–0.044, p = 0.001)). Conclusion. The results of our study showed a significant effect of the GSTT1 and GSTM1 gene deletion polymorphism on relapse-free survival in patients with stage III disease and hormone-dependent breast cancer.