CA 125

CA 125
Start Date
Expiration Date
Cancer Antigen 125, OV-125
CPT Codes
Main Lab
Reference Test
ATLAS Test Code


Specimen Information


Gold, SST


1.0 ml

Transport Info

Refrigerated 5 day stability, frozen 3 month stability

Fasting Required?
Patient Instructions

Reference Range


0-35 U/mL



Clinical Significance

Detect residual ovarian carcinoma in patients who have undergone first-line therapy. It is considered a one-time test to determine the possibility of second look procedures. Immunoassay for the in vitro quantitative determination of OC 125 reactive determinants in human serum and plasma. These determinants are associated with a high molecular weight glycoprotein in serum and plasma of women with primary epithelial invasive ovarian cancer (excluding those with cancer of low malignant potential). The CA 125 II assay is indicated for use as an aid in the detection of residual or recurrent ovarian carcinoma in patients who have undergone first-line therapy and would be considered for second-look procedures. The CA 125 II assay is further indicated for serial measurement of CA 125 to aid in the management of cancer patients.CA 125 belongs to the family of hybridoma-defined tumor markers. The values measured are defined by the use of the monoclonal antibody (MAb) OC 125. The antigenic determinant CA 125 is located on a high-molecular weight glycoprotein (200-1000 kD) isolated from cell culture or serum. The antigenic determinant CA 125 has a protein structure with associated carbohydrate side-chains.CA 125 is found in a high percentage of non-mucinous ovarian tumors of epithelial origin and can be detected in serum. It does not occur on the surface epithelium of normal ovaries (adult and fetal). Ovarian carcinoma accounts for about 20% of gynecological tumors; the incidence is 15/100,000.CA 125 has been found in the amnion and in the coelomic epithelium; both of these tissues are of fetal origin. In tissues of adult origin, the presence of CA 125 has been demonstrated in the epithelium of the oviduct, in the endometrium and in the endocervix.Elevated values are sometimes found in various benign gynecological diseases such as ovarian cysts, ovarian metaplasia, endometriosis, uterus myomatosus and cervicitis. Slight elevations of this marker may also occur in early pregnancy and in various benign diseases (e.g. acute and chronic pancreatitis, benign gastrointestinal diseases, renal insufficiency, autoimmune diseases and others). Markedly elevated levels have been found in benign liver diseases such as cirrhosis and hepatitis. Extreme elevations can occur in any kind of ascites due to malignant disease. Although the highest CA 125 values occur in patients suffering from ovarian carcinoma, clearly elevated values are also observed in malignancies of the endometrium, breast, gastrointestinal tract and various other malignancies.Although CA 125 is a relatively unspecific marker, it is today the most important tumor marker for monitoring the therapy and progress of patients with serous ovarian carcinoma. At primary diagnosis, the sensitivity of CA 125 depends on the FIGO stage (FIGO = Federation of Gynecology and Obstetrics); higher tumor stages are associated with higher CA 125 levels.