EBM Consult

Lab Test: CA 125 Level

    Lab Test
    • CA 125 measurement
    • Serologic tumor marker for monitoring clinical course of endometrial and ovarian cancer
    Reference Range
    • Adults:  0-35 units/mL (0-35 kilounits)/L
    Indications & Uses
    • Assessment of stage in endometrial cancer  using the International Federation of Gynceologists and Obstetricians (FIGO) staging, mean CA-125 value found in:
      • Early stages I and II was 42.7 International Units/mL
      • Advanced stage III and IV was 346.9 International Units/mL
    • When measured against grade, a similar correlation existed:  CA-125 levels (in International Units/mL) were:
      • 21.02 for grade 1
      • 82.35 for grade 2
      • 245 for grade 3
    • Evaluation of response to ovarian cancer treatment and assessment for recurrence - a falling level can be associated with a positive response to treatment, whereas a rising level can indicate progressive disease or treatment failure.  A false decrease in the level is possible while undergoing therapy, as is a negative result with tumor recurrence.
    Clinical Application

    This tumor marker has a high degree of sensitivity and specificity for ovarian cancer and is known to be an accurate marker for nonmucinous epithelial tumors of the ovary.  It is elevated in more than 80% of women with ovarian cancer, however, by itself, it should not be used to diagnose ovarian cancer, but rather is supportive of the diagnosis.  It can also be used to determine a patient's response to therapy. 

    Related Tests
    • Carcinoembryonic antigen - this tumor marker can be elevated in ovarian epithelial tumors.
    • Alpha-fetoprotein - this tumor marker is elevated in nonepithelial ovarian tumors.
    • Human chorionic gonadotropin - this tumor marker is elevated in nonepithelial ovarian tumors.
    Drug-Lab Interactions
    • Bexarotene - elevated CA 125 assay values
    • Satumomab Pendetide - falsely elevated levels of CA 125
    • Technetium Tc 99 m Nofetumomab Merpentan - interference with urine antibody-based immunoassays
    • Results increased in:  endometriosis, menses, pelvic inflammatory disease, pregnancy
    • Patients with mild peritoneal diseases (e.g., cirrhosis, endometriosis) will have mildly increased levels
    • Smoking can falsely increase CA-125 levels.
    • Patients who have had recent abdominal surgery may have elevated CA-125 levels for as long as 3 weeks after surgery. 

    Increased levels indicate:

    • Malignant disorders, such as cancer of the ovary, cancer of the pancreas, cancer of the colon, cancer of the lung, peritoneal carcinomatosis, cancer of the nonovarian female genital tract, cancer of the breast, or lymphoma.
    • Benign disorders, such as cirrhosis, peritonitis, pregnancy, endometriosis, pancreatitis, pelvic inflammatory disease (PID).
    Test Tube Needed
    • Red top tube
    • Collect a venous of blood sample. 
    • The blood may be sent to a central diagnostic laboratory for determination of CA-125 level.
    • The results are available to the local hospital in 3 to 7 days.
    • Apply pressure or a pressure dressing to the venipuncture site and observe the site for bleeding.
    What To Tell Patient Before & After
    • Explain the procedure to the patient.
    • Tell the patient that no fasting or sedation is required.
    • Provide emotional support to the patient.  Cancer testing is very stressful.
    • LaGow B et al., eds. PDR Lab Advisor. A Comprehensive Point-of-Care Guide for Over 600 Lab Tests.  First ed. Montvale, NJ: Thomson PDR; 2007.
    • Pagana K, Pagana TJ eds. Mosby's Manual of Diagnostic and Laboratory Tests. 5th Ed.  St. Louis, Missouri. 2014.

MESH Terms & Keywords

  • CA 125