Clinical significance:

CA-125 is a large glycoprotein which promotes cancer cell proliferation and inhibits anticancer immune responses. CA-125 is found in high percentage of ovarian tumors of epithelial origin(non mucinous) and can be detected in serum.

This test can be used to:

  • Check if ovarian cancer is still present after treatment.
  • See how well a cancer patient is responding to treatment.
  • Look for signs of cancer recurrence.

Clinical uses:

1. Aids in detection of residual or recurrent ovarian carcinoma in patients who have undergone first line therapy.

2 .CA-125 in conjunction  with HE4 assay is used to calculate ROMA index ( risk of ovarian malignancy algorithm) to determine whether  the pelvic mass is benign or malignant in pre & postmenopausal  women1,2.

Reference range for CA-125-

The normal range for CA-125 in women who are not pregnant is 0-35 U/mL


CA-125 is Increased in following conditions

Non mucinous epithelial ovarian carcinoma,

Elevated CA-125 values are sometimes found in various benign diseases such as ovarian cysts endometriosis, ovarian metaplasia, autoimmune oophoritis, endometriosis,  pancreatitis,  cirrhosis of liver, benign gastrointestinal diseases.

Other cancerous conditions with elevated CA125 are malignancies of the endometrium, breast, and gastrointestinal tract.

Sequential determinations are more useful than single test , because progressive rise occurs in malignant disease.

Slight elevations of CA-125 may occur in early pregnant and various benign diseases.


This test may exhibit interference when the sample is collected from a person who is consuming a high dose of biotin (>5mg/day) Patients should be cautioned to stop biotin consumption at least 8 hours before collection of the sample.

In rare cases heterophile antibodies in serum can react with reagent immunoglobulin and cause interference in results, particularly seen in persons exposed to animals and animal serum products .


1.Moore RG, Brown AK, Miller MC, et al. The use of multiple novel tumor biomarkers for the detection of ovarian carcinoma in patients with a pelvic mass. Gynecol Oncol 2008;108(2):402-408

2.Huhtinen K, Suvitie P, Hiissa J, et al. Serum HE4 concentration differentiates malignant ovarian tumours from ovarian endometriotic cysts. Br J Cancer 2009;100(8):1315-1319.

3.Mosby’s Diagnostic and Laboratory Test Reference, 16th Edition .

4.Tietz  fundamentals of clinical chemistry and molecular diagnostics,8th edition

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