Abstract Potassium bromate (KBrO3) is by-product of ozone that has found multifunctional purpose in modern society. It is used as disinfectant in drinking water, a bleaching agent to improve flour, a component of cold-wave hair lotion and an ingredient in the production of fish paste and fermented beverages. Potassium bromide has also been used in America for bread-baking as a safe food additive since 1914. Despite the commercial value of this chemical, some studies suggest that KBrO3 could be a carcinogen. During the bread-baking process, Potassium bromate is normally converted into a stable and inert compound, potassium bromide (KBr). However, due to incomplete reduction, the residual KBrO3 remains in the bread, which eventually acts as a potential carcinogen to humans. Interestingly, our studies, in breast cancer cells, found contrasting results. We found that KBrO3 delays growth of ER-α positive luminal type breast cancer cells and triple-negative breast cancer cells (TNBC) via inducing apoptosis in a dose-dependent manner. KBrO3-induced apoptosis is mediated via targeting BCL-2/Bax and Caspase-3 signaling pathway. Moreover, aggressive phenotypes such as migration, invasion and sphere-forming ability of breast cancer cells are significantly impaired by KBrO3-treatment via targeting multiple molecular signatures in breast cancer cells. The growth inhibition effect of KBrO3 is also documented in a tumor xenograft model. Collectively, our findings provide a rationale for the basic and pre-clinical evaluation of the role of KBrO3 in breast cancer progression and therapy. Citation Format: Priyanka Ghosh, Gargi Maity, Snigdha Banerjee, Sushanta Banerjee. The food additive agent potassium bromate prevents growth and aggressive phenotypes by targeting multiple molecular signatures in breast cancer cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 2118. doi:10.1158/1538-7445.AM2017-2118