CA9 and ductal breast carcinoma in situ: There was no evidence that CA IX expression was associated with known prognostic variables, specifically tumour size (P=0.13), DCIS grade (P=0.89), axillary lymph node status (P=0.38), and ER status (P=0.11), side of tumour (0.50), surgery type (P=0.13), vascular invasion (P=0.59), tumour grade (0.40), and Nottingham Prognostic Index (P=0.39).