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Last reviewed dd mmm yyyy. Last edited dd mmm yyyy

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Cancer Antigen 125 (CA125), also referred to as Carbohydrate Antigen 125:

  • elevated in 50% of early-stage ovarian tumours and 92% of advanced-stage tumours (1)

  • in general, about 20% of ovarian cancers have no CA125 expression (1)

  • CA125 is present in ovaries' embryonic development but disappears in the course of development and is then re-expressed in ovarian neoplasms
    • because CA125 is produced by tissues derived from coelomic epithelium, elevations may be seen in the peritoneal and pleural epithelial and ascites fluids
    • been reports of elevated levels of soluble CA125 in a number of other malignant conditions such as (2):
      • breast cancer
      • lung cancer
      • mesothelioma
      • non-Hodgkin lymphoma (NHL)
      • gastric cancer
      • and leiomyoma and leiomyosarcoma of gastrointestinal origin

  • CA125 levels have been found elevated in benign conditions such as (2):
    • endometriosis
    • pregnancy
    • levels of CA125 are substantially higher in healthy premenopausal women (1)
    • ovulatory cycles
      • levels rise during the premenstrual phase and are higher in healthy women with anovulatory cycles (1)
    • liver diseases
      • elevations in CA125 concentrations are also observed in 85% of patients with cirrhosis, and detectable levels are seen in ascites fluid from patients with chronic liver disease (1)
    • congestive heart failure
    • in infectious disease such as tuberculosis

  • cohort study of over 50,000 women who underwent CA125 testing in English general practice (3)
    • 10.1% of those with a CA125 at or above the conventional cutoff (35 U/ml) were diagnosed with ovarian cancer

    • 12.3% with a CA125 >= 25 U/ml were diagnosed with a different cancer

    • almost a third of women aged >= 50 years with a CA125 >=35 U/ml were diagnosed with some form of cancer

    • a CA125 level of 53 U/ml equated to an overall ovarian cancer probability of 3%
      • marked variation was noted between women of different ages, with the 3% probability reached at lower CA125 levels in 70-year-old women than younger or older women
      • ovarian cancer probability of 3% equated to a value of 104 U/ml in 40-year-old women and 32 U/ml in 70-year-old women


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