Since FOXP3 is the single most accurate marker of regulatory T cells (Tregs),46 the high expression of FOXP3+ cells in a proportion of DCIS in addition to high expression of PDL1 suggests an immunosuppressive environment being created simultaneously in early tumour development, in concordance with previous studies.47–49 A recent review by Chen et al. summarised findings from previous work that support our study findings, such as high grade DCIS harbouring more TILs than low grade lesions and being associated with underlying genetic alterations.50 The gene discussed is CD274; the disease is ductal breast carcinoma in situ.