TLR9 and neoplasm: Our studies in pre-clinical cancer models however demonstrated that despite slower in vitro growth, TNBC cells with low TLR9 expression formed in vivo significantly larger tumors than those with high TLR9 expression.[15] Notably, all our previous (Caucasian) cohorts consisted of patients of European ethnicity, from Northern and Eastern Finland.[15, 33] Ethnicity of the patients with results similar to ours was not disclosed in the French cohort.[32] Despite these promising results, tumor TLR9 expression is not currently used as a prognostic clinical tool.