ca - 125

Last edited 11/2023 and last reviewed 11/2023

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

Reference:

• Charkhchi P, Cybulski C, Gronwald J, Wong FO, Narod SA, Akbari MR. CA125 and Ovarian Cancer: A Comprehensive Review. Cancers (Basel). 2020 Dec 11;12(12):3730. doi: 10.3390/cancers12123730.
• Scholler N, Urban N. CA125 in ovarian cancer. Biomark Med. 2007 Dec;1(4):513-23. doi: 10.2217/17520363.1.4.513.
• Funston G, Hamilton W, Abel G, Crosbie EJ, Rous B, Walter FM. The diagnostic performance of CA125 for the detection of ovarian and non-ovarian cancer in primary care: A population-based cohort study. PLoS Med. 2020 Oct 28;17(10):e1003295.