Cancer antigens are substances detected in serum or tissue and are defined by one or two monoclonal antibodies. Immunologic methods are used to detect the substances in serum and immunohistochemical methods in tissue. Assay kits for these markers are available to ensure consistent values among agencies performing the tests. These tumor markers are not used for screening malignancy in asymptomatic populations.

CA 15-3 is a serum antigen defined by two monoclonal antibodies found in breast cancer and breast cancer metastasis to the liver as well as in benign diseases of the breast. CA 19-9 is a serum antigen defined by a monoclonal antibody found in malignancies of the pancreas, gallbladder, salivary glands, and endocervix as well as in benign disorders such as acute pancreatitis, inflammatory bowel disease, and hepatobiliary disease. The test is commonly performed to monitor the course of a malignancy that is known to produce the antigen. CA 50 is a serum antigen defined by a monoclonal antibody found in pancreatic, colorectal, and gastrointestinal malignancies. Besides its diagnostic value, CA 50 is used to monitor the course of a tumor that produces the antigen.

CA 125 is a serum antigen defined by a monoclonal antibody found in ovarian and pelvic organ malignancies as well as in breast and pancreatic malignancies. Nonmalignant conditions such as ascites of benign cause, pregnancy, menstruation, endometriosis, and pelvic inflammatory disease also cause increases in this antigen. The test is undertaken to monitor surgical removal of malignant ovarian tumor for recurrence and metastasis. Another test, tissue polypeptide antigen (TPA), is a marker identified in serum and tissue in those with a variety of malignancies in relation to the extent of the disease and subsequent recurrence or regression after surgical removal of the tumor.⁴²

• Chemotherapeutic agents administered to treat tumor.
• Levels can be increased in the absence of disease or in benign disorders and can affect diagnostic findings for malignancy.

• Diagnosis and confirmation of presence of local and metastatic malignancy, suggested by an increased level or a gradual rise in levels of the specific cancer antigen
• Determination of residual tumor after surgical intervention to remove the malignancy
• Monitoring of course of the malignancy and effectiveness of therapeutic regimen to determine progression, prognosis, or recurrence
• Differentiation between malignant and benign disorders of specific organ tissues

Nursing Care Before the Procedure

Client preparation is the same as for any study involving the collection of a peripheral blood sample (see Appendix I).

• Obtain a history regarding the presence of other acute or chronic diseases and the assessment data that support the diagnoses.
• Ensure that neoplastic medication protocols are administered.

A venipuncture is performed and the sample collected in a red-topped tube. The sample should be transported promptly to the laboratory for analysis by immunoassay methods.

Nursing Care After the Procedure

Care and assessment after the procedure are the same as for any study involving the collection of a peripheral blood sample.

• Abnormal values: Note and report increased values or return of increased values. Assess for presence of malignancy site or metastasis or both, past or ongoing treatments, and procedures for malignancy. Assist client and family to reduce anxiety and to cope with need for additional treatments or poor prognosis.