CA9 and in situ carcinoma: IHC detection of CA IX protein in the non-treated CIS subgroup had four (50%) and seven (38.9%) negative samples in the paclitaxel and doxorubicin group, respectively, while the IC subgroup had three (60%) negative samples in the paclitaxel group and seven (63.6%) negative samples in the doxorubicin group (Table 2).