Median (range) levels of total and FL mRNA were as follows: total CAIX was 66 (2.5–235) copies/mL in bladder cancer patients vs. 810 (130–1130) copies/mL in controls; FL CAIX was 22 (0.6–235) copies/mL in bladder cancer patients vs. 3 (2.4–7) copies/mL in controls. Here, CA9 is linked to urinary bladder cancer.