CA9 and neoplasm: Moreover, after adjustment by age, grade, tumour size and lymph node positivity, there is a significant difference between positive CAIX expression and negative CAIX expression in TNBC patients on their survival outcomes ([OS: HR = 2.99, 95% CI = 1.78–5.02, P < 0.001], and [DFS: HR = 2.56, 95% CI = 1.41–4.65, P = 0.002]).