CA9 and neoplasm: Accordingly, ELISA analyses of serum samples from patients from our institution showed the following values: Increased CA9 levels (95% CI) of 237 (31–443) pg/ml in metastatic patients (n = 9), and of 112 (74–151) pg/ml in non-metastatic patients with high tumor load (tumors larger than 9 cm; n = 15), as compared to a concentration of 54 (26–83) pg/ml in subjects with T1a stage tumors (n = 14); p = 0.0069.