CD4 and cancer: Moreover, when testing the associations of the bacterial composition with the immune cell proportions of the other cancer types, we detected several interesting associations: Tregs were associated with the majority of the cancer types (COAD, LUAD, LUSC, HNSC and BRCA), followed by dendritic cells (COAD, READ, HNSC and BRCA) and resting CD4 memory T cells (COAD, LUAD, HNSC and BRCA), while monocytes and neutrophils are examples of immune cell subtypes associated with a specific cancer type (BRCA and HNSC respectively), see Additional file 1: Fig. S10 for details.