At a Glance
Why Get Tested?
To monitor treatment for ovarian cancer or to detect recurrence; sometimes to evaluate a pelvic mass; not recommended for screening asymptomatic women but sometimes ordered to help detect early ovarian cancer in those identified as being at high risk
When to Get Tested?
Before starting therapy for ovarian cancer and at intervals during and after treatment; sometimes when you have a pelvic mass or are at a high risk for developing ovarian cancer
A blood sample drawn from a vein in your arm
Test Preparation Needed?
The Test Sample
What is being tested?
The Cancer Antigen 125 (CA-125) test measures the amount of CA-125 in the blood. CA-125 is a protein that is present on the surface of most, but not all, ovarian cancer cells. This makes the test useful as a tumor marker in specific circumstances.
Significantly elevated concentrations of CA-125 may be present in the blood of a woman who has ovarian cancer. Small quantities of CA-125 are produced by normal tissues throughout the body and by some other cancers. Levels in the blood may be moderately elevated with a variety of non-cancerous conditions, including menstruation, pregnancy, and pelvic inflammatory disease.
How is the sample collected for testing?
A blood sample is obtained by inserting a needle into a vein in the arm.
NOTE: If undergoing medical tests makes you or someone you care for anxious, embarrassed, or even difficult to manage, you might consider reading one or more of the following articles: Coping with Test Pain, Discomfort, and Anxiety, Tips on Blood Testing, Tips to Help Children through Their Medical Tests, and Tips to Help the Elderly through Their Medical Tests.
Another article, Follow That Sample, provides a glimpse at the collection and processing of a blood sample and throat culture.
Is any test preparation needed to ensure the quality of the sample?
No test preparation is needed.
Ask a Laboratory Scientist
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NOTE: This article is based on research that utilizes the sources cited here as well as the collective experience of the Lab Tests Online Editorial Review Board. This article is periodically reviewed by the Editorial Board and may be updated as a result of the review. Any new sources cited will be added to the list and distinguished from the original sources used.
Sources Used in Current Review
(Updated 2012 August 1). Fazal Hussain, F. and Homoud, H. Gynecologic Tumor Markers Tumor Marker Overview. Medscape Reference [On-line information]. Available online at http://emedicine.medscape.com/article/269839-overview through http://emedicine.medscape.com. Accessed October 2012.
Zieve, D. and Chen Y. (Updated 2011 December 15). CA-125. MedlinePlus Medical Encyclopedia [On-line information]. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/007217.htm. Accessed October 2012.
(Revised 2012 October 5). Can ovarian cancer be found early? American Cancer Society [On-line information]. Available online at http://www.cancer.org/cancer/ovariancancer/detailedguide/ovarian-cancer-detection through http://www.cancer.org. Accessed October 2012.
Grenache, D. et. al. (Updated 2012 May). Ovarian Cancer. ARUP Consult [On-line information]. Available online at http://www.arupconsult.com/Topics/OvarianCancer.html?client_ID=LTD through http://www.arupconsult.com. Accessed October 2012.
Schmidt, C. (2011 December 05). CA-125: A Biomarker Put to the Test. Medscape Today News from J Natl Cancer Inst. V 103(17):1290-1281 [On-line information]. Available online at http://www.medscape.com/viewarticle/750770 through http://www.medscape.com. Accessed October 2012.
Rustin, G. et. al. (2012 March 08). CA-125: To Monitor or Not to Monitor? For Ovarian Cancer Patients in Remission. Medscape Today News [On-line information]. Available online at http://www.medscape.com/viewarticle/759809 through http://www.medscape.com. Accessed October 2012.
(2012 September). Screening for Ovarian Cancer, U.S. Preventive Services Task Force Reaffirmation Recommendation Statement. USPSTF [On-line information]. Available online at http://www.uspreventiveservicestaskforce.org/uspstf12/ovarian/ovarcancerrs.htm through http://www.uspreventiveservicestaskforce.org. Accessed November 2012.
Pagana, K. D. & Pagana, T. J. (© 2011). Mosby's Diagnostic and Laboratory Test Reference 10th Edition: Mosby, Inc., Saint Louis, MO. Pp 210-211.
Clarke, W., Editor (© 2011). Contemporary Practice in Clinical Chemistry 2nd Edition: AACC Press, Washington, DC. Pp 499-500.
Sources Used in Previous Reviews
Thomas, Clayton L., Editor (1997). Taber's Cyclopedic Medical Dictionary. F.A. Davis Company, Philadelphia, PA [18th Edition].
Pagana, Kathleen D. & Pagana, Timothy J. (2001). Mosby's Diagnostic and Laboratory Test Reference 5th Edition: Mosby, Inc., Saint Louis, MO.
Pagana, K. D. & Pagana, T. J. (© 2007). Mosby's Diagnostic and Laboratory Test Reference 8th Edition: Mosby, Inc., Saint Louis, MO. Pp 219-220.
Wu, A. (© 2006). Tietz Clinical Guide to Laboratory Tests, 4th Edition: Saunders Elsevier, St. Louis, MO. Pp 210-211.
Mason, J. (Updated 2008 June 10). CA-125. MedlinePlus Medical Encyclopedia. [On-line information]. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/007217.htm. Accessed March 2009.
(2007 March). Ovarian Cancer Resource Guide for women with recurrent disease. NOCC, Inc. [On-line information]. PDF available for download at http://www.ovarian.org/Images/ResourceGuideRecurrentOvarianCancer.pdf through http://www.ovarian.org. Accessed March 2009.
(2008 August 26). Ovarian Cancer: Why Screening Isn't Routine. American Cancer Society. [On-line information]. Available online at http://www.cancer.org/docroot/SPC/content/SPC_1_ovarian_Q_A_Saslow.asp through http://www.cancer.org. Accessed March 2009.
(Modified 2008 April 3). Ovarian Cancer Screening (PDQ®), Health Professional Version. NCI, U.S. National Institutes of Health. [On-line information]. Available online at http://www.cancer.gov/cancertopics/pdq/screening/ovarian/healthprofessional through http://www.cancer.gov. Accessed March 2009.
(2008 July). Understanding CA 125 Levels: A Guide for Ovarian Cancer Patients. Gynecologic Cancer Foundation. [On-line information]. PDF available for download at http://www.thegcf.org/wcnlib/downloads/CA125levels_July2008.pdf through http://www.thegcf.org. Accessed March 2009.