Objective  To investigate the expression of carbohydrate antigen 125 (CA125), its association with other markers, and their clinical significance in a variety of populations using protein chip detective systems.

  Methods  A total of 25, 076 cases detected with multiple tumor marker chips from 2004 to 2011 were collected. The expression levels of CA125 and its association with other markers were analyzed in various populations and patients with different types of tumor.

  Results  CA125 expression was significantly elevated in patients with malignant tumors compared with patients with benign disease and healthy individuals. The CA125 positive rate appeared to be the highest in ovarian cancer (59.72%), followed by that in pancreatic (49.25%) and liver (42.56%) cancers. The most common accompanying marker was CEA; other less common markers were CA199, CA242, and ferritin. The CA125/CEA combination occurred most frequently in colorectal cancer (83.87%) followed by breast cancer (59.72%). CA125/CA199 was most prevalent in colorectal (90.97%) and pancreatic (78.63%) cancers. CA125/CA242 frequently appeared in colorectal (92.26%) and pancreatic (74.81%) cancers. CA125+CEA+CA199 and CA125+CEA+CA199+CA242 increase were most common in lung cancer.

  Conclusion  Elevated CA125 is a good indicator of ovarian, pancreatic, and liver cancers. The detection of CA125 combined with CEA, CA199, and CA242 has significance in improving the diagnosis of colorectal, pancreatic, and lung cancers.