Cancer Antigen 125

Aka: Cancer Antigen 125, CA-125, CA 125

1. Indications
   1. Postmenopausal pelvic mass evaluation
   2. Ovarian Cancer serial monitoring
   3. Not a Screening Test for cancer (insensitive)
      1. May obtain baseline if Ovarian Cancer high risk
2. Interpretation (CA 125 level in units/ml)
   1. Normal: CA-125 less than 35 (Does not exclude cancer)
   2. Increased
      1. CA-125 >35 highly correlated with cancer (epithelial Ovarian Cancer cell line)
         1. Used as oncology referral indication for post-menopausal women
      2. CA-125 >65 associated with cancer in 90% of pelvic masses
      3. CA-125 >200 unlikely to be due to benign condition
         1. Used as oncology referral indication for pre-menopausal women
3. Efficacy (ranges are approximate with high values more attributed to post-menopausal patients)
   1. Positive Predictive Value: 35-91%
   2. Negative Predictive Value: 67-90%
   3. Test Specificity
      1. Pre-Menopause: 71%
      2. Post-Menopause: 93%
   4. Test Sensitivity
      1. Pre-Menopause: 61%
      2. Post-Menopause: 90%
      3. Stage I disease: 50%
      4. Advanced disease: 90%
4. Causes: Increased
   1. Non-Cancer Causes
      1. Endometriosis
      2. Pelvic Inflammatory Disease
      3. Uterine Fibroids
      4. Pregnancy
      5. Menstruation
      6. Functional Ovarian Cyst
      7. LiverCirrhosis
      8. Post-Menopause
      9. Tuberculous Peritonitis
      10. Pelvic Irradiation
   2. Malignant Causes
      1. Ovarian Cancer
      2. Liver Cancer
      3. Lung Cancer
      4. Breast Cancer
      5. Colon Cancer
      6. Pancreatic Cancer
      7. Endometrial Cancer
      8. Cervical Cancer
5. References
   1. (2002) Obstet Gynecol 100(6):1413-6
   2. Tuxen (1995) Cancer Treat Rev 21:215-45
   3. Jacobs (1999) Lancet 353:1207-10
   4. Sevinc (2007) Lancet Oncol 8(12): 1054-5