A CA 125 test measures the amount of the protein CA 125 (cancer antigen 125) in your blood.
A CA 125 test may be used to monitor certain cancers during and after treatment. In some cases, a CA 125 test may be used to look for early signs of ovarian cancer in women with a very high risk of the disease.
A CA 125 test isn't accurate enough to use for ovarian cancer screening in all women because many noncancerous conditions can increase the CA 125 level.
Many different conditions can cause an increase in CA 125, including normal conditions, such as menstruation, and noncancerous conditions, such as uterine fibroids. Certain cancers may also cause an increased level of CA 125, including ovarian, endometrial, peritoneal and fallopian tube cancers.
April 14, 2014
- CA-125. Lab Tests Online. http://labtestsonline.org/understanding/analytes/ca125/tab/glance. Accessed Dec. 10, 2013.
- Understanding CA 125 levels: A guide for ovarian cancer patients. Foundation for Women's Cancer. http://www.foundationforwomenscancer.org/educational-materials/ovarian-cancer. Accessed Dec. 10, 2013.
- Tumor markers: Questions and answers. National Cancer Institute. http://www.cancer.gov/cancertopics/factsheet/detection/tumor-markers. Accessed Dec. 10, 2013.
- Cancer antigen 125 (CA 125), serum. Mayo Medical Laboratories. http://www.mayomedicallaboratories.com/test-catalog/Clinical+and+Interpretive/9289. Accessed Dec. 11, 2013.
- Moyer VA, et al. Screening for ovarian cancer: U.S. Preventive Services Task Force reaffirmation recommendation statement. Annals of Internal Medicine. 2012;157:900.
- Buys SS, et al. Effect of screening on ovarian cancer mortality: The Prostate, Lung, Colorectal and Ovarian (PLCO) cancer screening randomized controlled trial. JAMA. 2011;305:2295.
- Reade CJ, et al. Risks and benefits of screening asymptomatic women for ovarian cancer: A systematic review and meta-analysis. Gynecologic Oncology. 2013;130:674-681.
- Genetic/familial high-risk assessment: Breast and ovarian. Fort Washington, Pa.: National Comprehensive Cancer Network. http://www.nccn.org/professionals/physician_gls/f_guidelines.asp. Accessed Dec. 3, 2013.
- Ovarian cancer including fallopian tube cancer and primary peritoneal cancer. Fort Washington, Pa.: National Comprehensive Cancer Network. http://www.nccn.org/professionals/physician_gls/f_guidelines.asp. Accessed Dec. 3, 2013.