Abstract 6833: Influence of g<i>uthation S transferase</i> T1 and M1 polymorphisms on tamoxifen metabolism in malian women with breast cancer

Abstract Background: The metabolism of tamoxifen, used in breast cancer treatment, is influenced by the GSTT1 and GSTM1 genes. Women were classified as poor (inactivated genes), intermediate (reduced enzyme activity), or rapid (functional genes) metabolizers. This classification helped to understand how genetic variations affected treatment efficacy and side effect risk, promoting a personalized therapeutic approach. This study aimed to analyze the impact of GSTT1 and GSTM1 genetic variations on tamoxifen metabolism in Malian women with breast cancer. Methods: A cohort study was conducted involving 109 Malian women (ages 18-50) diagnosed with ER/PR (+) breast cancer and eligible for tamoxifen treatment. GSTM1 and GSTT1 genotypes were determined using multiplex PCR. Results: A significant correlation was observed between the GSTM1 gene and family history of breast cancer (p = 0.026) as well as tumor size (p = 0.031). The genotypic frequencies were 75.2% for functional GSTM1 and 24.8% for inactive; for GSTT1, 56.9% were functional and 43.1% inactive. The categories of metabolizers were distributed as follows: 42.2% (rapid), 14% (intermediate), and 11% (poor), with a significant difference (p &amp;lt; 0.0001). Conclusion: This study highlights the correlation between the GSTM1 and GSTT1 genes and factors related to breast cancer. Genotypic variations affect tamoxifen metabolism, emphasizing the importance of genetic factors in optimizing treatment. Citation Format: Brehima Diakite, Yaya Kassogue, Mamoudou Maïga, Oumar Kassogue, Fousseyni Diarra, Kadidiatou Cisse, Aissata Coulibaly, Cheick B. Traore, Madani Ly, Jane L. Holl, Lifang Hou. Influence of guthation S transferase T1 and M1 polymorphisms on tamoxifen metabolism in malian women with breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 6833.