Serum CA50 levels in patients with cancers and other diseases

Carbohydrate antigen 50 (CA50) is initially reported as a cancer-specific antigen expressed on the surface of human colorectal Colo-205 cancer cells. Subsequently, increased serum CA50 levels are observed in patients not only with colorectal cancers but also other types of cancers. Eventually, serum CA50 is measured clinically as a cancer biomarker. However, serum CA50 level does not always increase in cancer patients but does increase in patients suffering from nonneoplasm diseases, which indicates that serum CA50 is not produced by cancer cells exclusively. Therefore, the serum CA50 levels in patients suffering different types of diseases should be systematically compared in order to comprehend the molecular nature of serum CA50 as a biomarker. In our current study, we measured and analyzed serum CA50 levels from 2113 patients with 14 clinically defined diseases with at least 30 independent tests for each disease in addition to 13,997 serum samples from individuals who attend their annual physical examination as healthy controls. Based on the mean, median, and -Log₁₀p values, we found that patients suffering from pancreatic cancer, cirrhosis, pancreatitis, lung cancer, type 2 diabetes mellitus, and colon cancer had highest levels of serum CA50 while patients suffering from coronary heart disease, gastric cancer, and rectum cancer showed comparable serum CA50 levels to that of healthy controls. Moreover, patients with osteoporosis, anemia, or gastritis had lower serum CA50 levels than that of healthy controls. Furthermore, healthy individuals older than 65 years old had increased serum CA50 levels compared with that of healthy controls. Taken together, these data suggest that serum CA50 is likely to be a system malfunction biomarker, and the serum CA50 levels could be used as diagnostic biomarkers not only for cancers but also for other nonneoplasm diseases.