Prospective Case-Control Study to Evaluate the Role of Glutathione S Transferases (GSTT1 and GSTM1) Gene Deletion in Breast Carcinoma and Its Prognostic Significance.

Breast cancer is the most common cause of cancer death in women with the incidence rising in young women. GST gene polymorphisms are significant because of their role in the detoxification of both environmental carcinogens and also cytotoxic drugs used in therapy for breast cancer. The present study has been designed to identify the role of polymorphisms in GSTT1 and GSTM1 genes in the risk of development of breast cancer, in the prognostication of breast cancer, and in the prediction of response towards chemotherapy. Ninety-nine patients with breast cancer and 100 healthy controls with no history of cancer were taken from blood donors after informed consent. Epidemiological and clinical data was collected from participants and 5 ml of peripheral venous blood was collected for genotype analysis. Null genotype of GSTT1 was detected in 51.04 % of the controls in comparison to 20.2 % of patients with carcinoma breast, which was found to be statistically significant (OR 4.18; 95 % CI 2.01-8.75; P = 0.0001). GSTM1 gene deletion was also significantly more common among controls (60 %) than in patients with breast cancer (33 %) (OR 4.57; 95 % CI 2.20-9.51; P = 0.0001). Tumors more than 5 cm in size had greater tendency for GSTM1 gene expression (P value = 0.019), but other clinicopathological parameters did not show any correlation. GSTT1 and GSTM1 genes status did not show any association with response to chemotherapy. The results indicated the null genotype of both GSTT1 and GSTM1 to be protective for the development of carcinoma breast. None of the known etiological factors have any correlation with GSTT1 and GSTM1 gene deletion. Patients with small tumor size expressed GSTM1 gene deletion. Other tumor characteristics and clinicopathological parameters did not have any correlation with gene deletion.