CA9 and cancer: CAIX was positive only in a few malignant tumors (38%, mainly in nasopharyngeal carcinoma, lung adenocarcinoma and squamous cell carcinoma, kidney clear cell carcinoma, cervical squamous cell carcinoma, ovarian serous cystadenocarcinoma and malignant melanoma of thigh) and CANT (12.5%, mainly in stomach and skin) samples (Table 1).