CA9 and ductal breast carcinoma in situ: To ensure that cellular abundance and clinical covariates do not confound colocalization, we report that the difference in FOXP3+ CA9+ colocalization between IDC regions and pure DCIS samples is independent of abundance of FOXP3+ lymphocytes and CA9+ epithelial cells (which does not vary significantly between these groups: p = 0.44 and p = 0.48 respectively, Fig. 4c), ER status ER status (multivariate p value adjusted for ER status = 0.004) and grade (multivariate p value adjusted for DCIS grade = 0.01).