The detection of colorectal carcinomas with the use of CA-50 radioimmunoassay inhibition test

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.

Evaluation of carbohydrate antigen 50 in human serum using magnetic particle-based chemiluminescence enzyme immunoassay

A magnetic particles (MPs)-based chemiluminescence enzyme immunoassay (CLEIA) with high sensitivity, specificity, rapidity, and reproducibility was proposed for the evaluation of tumor marker, carbohydrate antigen 50 (CA50) in human serum. The immunomagnetic particles coated with anti-fluorescein isothiocyanate (FITC) antibody was used as dispersed solid phase for the immunoassay, which was based on a sandwich immunoreaction of FITC-labeled anti-CA50 antibody, CA50 antigen, and alkaline phosphatase (ALP)-labeled anti-CA50 antibody, and was based on a subsequent chemiluminescence reaction of ALP with 4-methoxy-4-(3-phosphate-phenyl)-spiro-(1,2-dioxetane-3,2'-adamantane) (AMPPD) solution. The CL emission intensity was directly proportional to the amount of analyte present in a sample solution. The effects of several physicochemical parameters, including the concentration of FITC-labeled anti-CA50 antibody, the dilution ratio of ALP-labeled anti-CA50 antibody, the volume of MPs and substrate, the immunoreaction time and other relevant variables upon the immunoassay were studied and optimized. The proposed method exhibited advantages in a lower minimum detectable concentration of 1.0 U mL(-1) with comparison to the commercially available immunoradiometric assay (IRMA), and showed a larger linear range of 0 to 300 U mL(-1), as well as less total assay time of only 50 min with comparison to both IRMA and microplate CLEIA. The coefficient of variation was less than 7 and 11% for intra- and inter-assay precision, respectively. This method has been successfully applied to the evaluation of CA50 in human serum with recoveries from 82 to 112%, and showed a good correlation with the commercially available CA50 IRMA.

Clinical evaluation of a new serum tumour marker CA 242 in pancreatic carcinoma

The aim of this study was to evaluate the new monoclonal tumour marker CA 242 in the diagnosis of pancreatic carcinoma and to compare it with the established markers CA 50 and CEA. Serum concentrations were determined in 113 patients with jaundice, in 20 patients with laboratory values suggesting cholestasis, and in 60 patients with a suspicion to have chronic pancreatitis. Twenty-four of these 193 patients had pancreatic carcinoma and two patients had carcinoma of papilla of Vater. The sensitivities of CA 242, CA 50 and CEA were 80.7%, 96.1%, and 92.3%, respectively. The specificities were 79.0%, 58.0%, and 59.2%. The sensitivities of combinations of CA 50 and CEA with CA 242 did not exceed the sensitivity of CA 50 alone. The specificity of CA 242 was improved by combining it with CEA (92.2%). The serum marker CA 242 seems to be less sensitive than CEA and CA 50 in the detection of pancreatic carcinoma, but it may prove useful because of its high specificity.

Serum levels of CA-50, CA-19.9, CA-125, neuron specific enolase and carcinoembryonic antigen in lung cancer and benign diseases of the lung

The serum levels of five markers (CA-50, CA-19.9, CA-125, Enolase (NSE) carcinoembryonic antigen (CEA) were studied in 96 lung cancer patients and in 60 patients with benign diseases of the lung: sensitivity was 0.44, 0.41, 0.54, 0.23 and 0.38 respectively; specificity was 0.67, 0.87, 0.47, 0.93 and 0.97 respectively. Serum levels of CA-125 over 20 U/ml were found in 74% of patients with acute pneumonia. A good parallel existed between the clinical evolution of lung cancer and the variations in the serum level of CA-50, CA-19.9 and NSE. Although the pretreatment result was elevated, successive assays of the marker allowed the clinical evolution to be followed. Conflicting results were found with CA-125 and to a lesser extent with CEA. A close correlation existed between the serum levels CA-50 and CA-19.9 in the 2 groups of patients. In the absence of a specific marker for lung cancer, complementary information can be provided by means of a simultaneous determination of CEA, NSE, CA-19.9--or CA-50--and CA-125.

A clinical study of CA-50 as a tumour marker for monitoring of colorectal cancer

Using a radioimmunoassay we have determined serum levels of the carcinoma-associated antigen CA-50 in 266 patients with colorectal cancer. Elevated CA-50 levels were found in Dukes' A (15%), Dukes' B (43%), Dukes' C (31%) and Dukes' D (65%). Patients who had developed a recurrence had 66% elevated levels. 25% of resected patients with no evidence of disease also had elevated CA-50 levels. From 139 patients operated on for a Dukes' A-C, a rise in CA-50 levels from the pre- to the 6-9 month post-operative sample was demonstrated in 12 cases in the absence of any clinical evidence for a recurrence. On follow-up, a recurrence later developed in all these cases with lead times of CA-50 titre rises ranging from 5 to 40 months. A rise in CA-50 levels after resection of a Dukes' A-C is indicative of a recurrence and may precede any clinical evidence of disease by several months or years. Data is also presented from 552 cases with colorectal cancer analysed with a immunoradiometric assay.

CA-50 as a tumour marker for monitoring colorectal cancer: antigen rises in patients postoperatively precede clinical manifestations of recurrence

Using a monoclonal antibody-based radioimmunoassay inhibition method we have determined preoperative serum levels of the carcinoma-associated carbohydrate antigen CA-50 in 266 patients with primary colorectal cancer. CA-50 levels exceeding the mean value for blood donor sera by more than 2 standard deviations (greater than or equal to 17 U/ml) were found in 47% of these patients, with 15%, 43% and 31% being elevated in patients with Dukes' A, Dukes' B and Dukes' C cancer, respectively, and 63% and 66% being elevated in patients with more advanced localized or disseminated cancer. Only 5% of patients with benign colorectal disease had elevated CA-50 level and these were patients with ulcerative colitis of a duration of more than 10 years. Among patients who had developed a recurrence after operation for a primary Dukes' A-C colorectal cancer 66% had elevated levels, and 25% of resected patients with no clinical evidence of disease at corresponding times after operation also had CA-50 levels above the normal concentrations. From 139 patients operated for a Dukes' A-C colorectal cancer a definitive rise in CA-50 levels from the pre- to a 6-9 months postoperative sample was demonstrated in 12 cases in the absence of any clinical evidence for a recurrence. On prolonged follow-up a clinically manifest recurrence later developed in all of these cases with lead times of CA-50 titre rises ranging from 5 to 40 months. Our findings suggest that a rise in CA-50 levels after resection of a Dukes' A-C primary colorectal cancer is indicative of a recurrence and may precede any clinical evidence of disease by many months or years. Thus CA-50 may be a clinically useful tool for monitoring of patients with colorectal cancer.