Synchronous DCIS samples presented higher levels of GLUT1 staining (p = 0.004) and lower levels of CA9 staining (p = 0.01) than pure DCIS samples (Fig. 3A, pairwise Mann–Whitney U tests of mean intensity scores [MIS], unadjusted p values); all other markers showed non-significant differences between groups. This evidence concerns the gene CA9 and ductal breast carcinoma in situ.