CA-125 Tumor Marker

CA-125 is a substance, which is used as a so-called tumor marker. This means that its blood concentration may be dependent on presence of certain malignant diseases.


CA-125 is a membrane glycoprotein that is present in the mucous membranes of the respiratory tract and in female genital tract. Its increased blood level is mainly associated with gynecological tumors. The examination is done from a small sample of venous blood.


The examination of CA-125 is used in diagnosis and in evaluation of therapeutic response in ovarian cancer. Of course, the confirmation of diagnosis can not be done only due to a positive tumor marker, but depends on gynecological exam and imaging methods such as ultrasound or computed tomography of the abdomen that confirms the affection of an ovary by tumor mass. Regular monitoring of CA-125 is advantageous in patients with already confirmed ovarian cancer, who are undergoing cancer therapy to evaluate its effectiveness and remission (decrease of CA-125), or recurrence (increase of CA-125) of the disease.


In addition to the ovarian cancer, CA-125 marker may be elevated in other tumors such as  cancer of the fallopian tubes, endometrial cancer, certain subtypes of lung cancer and breast cancer.


The main disadvantage is relatively low sensitivity and specificity of the CA-125. It may be increased in many non-malignant diseases such as pelvic infections, endometriosis, liver cirrhosis and type 2 diabetes. Regular changes of its concentration also occur during the menstrual cycle and pregnancy.


Jiri Stefanek, MD  Author of texts: Jiri Stefanek, MD
 Sources: basic text sources