Notably, breast cancers with at least one-copy APOBEC3B deletion had lower fraction of macrophages M2 compared to A3Bwt/wt breast cancers with mean fractions of 0.196 and 0.207, respectively, but this difference was only marginally significant (P = 0.04; Additional file 1: Table S6). This evidence concerns the gene APOBEC3B and breast cancer.