Carbohydrate Antigen (CA) 19-9

Overview:

Monitor gastrointestinal, pancreatic, liver, and colorectal malignancies

The measured CA 19-9 value of a patient's sample can vary depending on the testing procedure used. CA 19-9 values determined on patient samples by different testing procedures cannot be directly compared with one another and could be the cause of erroneous medical interpretations.

The determination of CA 19-9 cannot be used for the early detection of pancreatic carcinoma.1

Three percent to 7% of the population have the Lewis a-negative/b-negative blood group configuration and are unable to express the mucin with the reactive determinant CA 19-9. Patients known to be genotypically negative for Lewis blood group antigens will be unable to produce the CA 19-9 antigen even in the presence of malignant tissue. Phenotyping for the presence of the Lewis blood group antigen may be insufficient to detect true Lewis antigen-negative individuals. Even patients who are genotype positive for the Lewis antigen may produce varying levels of CA 19-9 as the result of gene dosage effect. This must be taken into account when interpreting the findings.2

As the mucin is excreted exclusively via the liver, even slight cholestasis can lead to clearly elevated CA 19-9 serum levels in some cases.

As with all tests containing monoclonal mouse antibodies, erroneous findings may be obtained from samples taken from patients who have been treated with monoclonal mouse antibodies or who have received them for diagnostic purposes.1 In rare cases, interference due to extremely high titers of antibodies to streptavidin and ruthenium can occur.1 The test contains additives, which minimize these effects.

For diagnostic purposes, the results should always be assessed in conjunction with the patient's medical history, clinical examination, and other findings.

This assay intended for the in vitro quantitative determination of CA 19-9 tumor-associated antigen in human serum and plasma.1 The assay is indicated for the serial measurement of CA 19-9 to aid in the management of patients diagnosed with cancers of the exocrine pancreas. The test is useful as an aid in the monitoring of disease status in those patients having confirmed pancreatic cancer who have levels of CA 19-9 at some point in their disease process exceeding the median concentration determined for the apparently healthy cohort.

The CA 19-9 values measured are defined by the use of the monoclonal antibody 1116-NS-19-9. The 1116-NS-19-9-reactive determinants on a glycolipid having a molecular weight of approximately 10,000 daltons are measured. This mucin corresponds to a hapten of Lewis-a blood group determinants and is a component of a number of mucous membrane cells.3,4

Mucin occurs in fetal gastric, intestinal, and pancreatic epithelia. Low concentrations can also be found in adult tissue in the liver, lungs, and pancreas.2,5

CA 19-9 assay values can assist in the differential diagnosis and monitoring of patients with pancreatic carcinoma (sensitivity 70% to 87%).6-12 There is no correlation between tumor mass and the CA 19-9 assay values; however, patients with CA 19-9 serum levels >10,000 units/mL almost always have distal metastasis.2

1. AFP a1-Fetoprotein on Elecsys 1010/2010 and Modular Analytics E170 [Package insert]. 2005-07, V1, Indianapolis, Ind: Roche Diagnostics; 2005.

2. Stieber P, Fateh-Moghadam A. Sensible Use of Tumor Markers. (Tumormaker und ihr sinnvoller Einsatz). Marloffstein-Rathsberg: Juergen Hartmann Verlag; 1993. Boehringer Mannheim, Cat. N° 1536869 (Engl), 1320947 (Deutsch). ISBN 3-926725-07-9 dtsch/engl.

3. Koprowski H, Steplewski Z, Mitchell K, Herlyn M, Herlyn D, Fuhrer P. Colorectal carcinoma antigens detected by hybridoma antibodies. Somatic Cell Genet. 1979 Nov; 5(6):957-971. PubMed 94699

4. Hansson GC, Zopf D. Biosynthesis of the cancer-associated sialyl-Lea antigen. J Biol Chem. 1985 Aug 5; 260(16):9388-9392. PubMed 4019478

5. Herlyn M, Sears HF, Steplewski Z, Koprowski H. Monoclonal antibody detection of a circulating tumor-associated antigen. Presence of antigen in sera of patients with colorectal, gastric, and pancreatic carcinoma. J Clin Immunol. 1982 Apr; 2(2):135-140. PubMed 7068815

6. Ritts RE Jr, Del Villano BC, Go VL, Herberman RB, Klug TL, Zurawski VR Jr. Initial clinical evaluation of an immunoradiometric assay for CA 19-9 using the NCI serum bank. Int J Cancer. 1984 Mar 15; 33(3):339-345. PubMed 6199316

7. Farini R, Fabris C, Bonvicini P, et al. CA 19-9 in the differential diagnosis between pancreatic cancer and chronic pancreatitis. Eur J Cancer Clin Oncol. 1985 Apr; 21(4):429-432. PubMed 3859414

8. Safi F, Roscher R, Beger HG. The clinical relevance of the tumor marker CA 19-9 in the diagnosing and monitoring of pancreatic carcinoma. Bull Cancer. 1990; 77(1):83-91. PubMed 2180502

9. Steinberg WM, Gelfand R, Anderson KK, et al. Comparison of the sensitivity and specificity of the CA 19-9 and carcinoembryonic antigen assays in detecting cancer of the pancreas. Gastroenterology. 1986 Feb; 90(2):343-349. PubMed 2416628

10. Fritsche HA Jr, Gelder FB. Serum tumor markers for pancreatic carcinoma. Immunol Ser. 1990; 53:289-296. PubMed 2100561

11. Steinberg W. The clinical utility of the CA-19-9 tumor-associated antigen. Am J Gastroenterol. 1990 Apr; 85(4):350-355. PubMed 2183589

12. Diamandis EP, Fritsche HA, Lilja H, et al. Tumor Markers: Physiology, Pathobiology, Technology, and Clinical Applications. 1st ed. Washington, DC: AACC Press; 2002.

Beretta E, Malesci A, Zerbi A, et al. Serum CA 19-9 in the postsurgical follow-up of patients with pancreatic cancer. Cancer. 1987 Nov 15; 60(10):2428-2431. PubMed 3478117

Pleskow DK, Berger HJ, Gyves J, Allen E, McLean A, Podolsky DK. Evaluation of a serologic marker, CA 19-9, in the diagnosis of pancreatic cancer. Ann Intern Med. 1989 May 1; 110(9):704-709. PubMed 2930108

Satake K, Kanazawa G, Kho I, Chung Y, Umeyama K. Evaluation of serum pancreatic enzymes, carbohydrate antigen 19-9, and carcinoembryonic antigen in various pancreatic diseases. Am J Gastroenterol. 1985 Aug; 80(8):630-636. PubMed 2411125

Shimomura C, Eguchi K, Kawakami A, et al. Elevation of a tumor-associated antigen CA 19-9 levels in patients with rheumatic diseases. J Rheumatol. 1989 Nov; 16(11):1410-1415. PubMed 2600938

Torosian MH. The clinical usefulness and limitations of tumor markers. Surg Gynecol Obstet. 1988 Jun; 166(6):567-579 (review). PubMed 2453934