Olive et al. [30] compared the CAIX and pimonidazole immunostaining in tumor sections from 18 cervical cancer patients and observed excellent colocalization and a strong correlation between the CAIX-positive and pimonidazole-positive tissue fractions, whereas in a similar study involving 42 patients, Airley et al. [31] did not find a significant correlation between CAIX expression and the level of pimonidazole binding. This evidence concerns the gene CA9 and cervical cancer.