Breast cancer (BC) is a heterogeneous and multifactorial disease. The system formed by glutathione-S-transferases (GSTs) acts to protect the organism against the oxidative stress generated by xenobiotics and their active products. Glutathione transferase mu 1 (GSTM1) and glutathione transferase theta 1 (GSTT1) present null polymorphic variants by complete deletion. The absence of these enzymes may influence the susceptibility to several diseases such as BC. This study aimed to systematically review and investigate the existence of a possible correlation between the presence/absence of these genetic variants and the development of BC and their influence in chemotherapy response. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) protocol was used, and the searches were performed in the portal of the Virtual Health Library (VHL) and the PubMed, resulting in 21 articles. It is clear that most studies revealed a risk association between the deletion of GSTM1 and/or GSTT1 and the development and/or prognosis of BC.Moreover, it should be noted that these results of risk association were found in large part in the populations of the Americas and Europe, followed by Asians. Regarding the response to treatment, protective associations were found in the presence of GSTM1 deletion. However, due to the inconclusive results of many studies, further analysis in this area is required.

乳腺癌（BC）是一种异质性和多因素疾病。由谷胱甘肽-S-转移酶（GST）形成的系统可保护生物体免受异源生物及其活性产物产生的氧化应激。谷胱甘肽转移酶mu 1（GSTM1）和谷胱甘肽转移酶theta 1（GSTT1））通过完全删除呈现无效的多态变体。这些酶的缺乏可能会影响对多种疾病（如BC）的敏感性。这项研究旨在系统地审查和调查这些遗传变异的存在与否与BC的发展及其对化疗反应的影响之间可能存在的相关性。使用了系统评价和荟萃分析的首选报告项目（PRISMA）协议，并且在虚拟健康库（VHL）和PubMed的门户中进行了搜索，得到21篇文章。显然，大多数研究表明，GSTM1和/或GSTT1缺失之间存在风险关联此外，应注意的是，这些风险关联的结果主要在美洲和欧洲的人群中发现，其次是亚洲人。关于对治疗的反应，在存在GSTM1缺失的情况下发现了保护性结合。但是，由于许多研究尚无定论，因此需要对该领域进行进一步分析。