While the effects of bacterially activated phytoestrogens on receptor positive BC are not yet agreed upon; a recent TNBC clinical trial, comprising 39 patients with invasive TNBC, established that a course of oral S‐equol inhibited proliferation of breast tumor cells, as measured by the cell proliferation marker Ki-67, with a 20% decrease in Ki‐67 expression in almost one third of patients (90). This evidence concerns the gene MKI67 and breast cancer.