Lab

Cancer Antigen 125

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Cancer Antigen 125, CA-125, CA 125

Indications

Postmenopausal pelvic mass evaluation
Ovarian Cancer serial monitoring
Not a Screening Test for cancer (insensitive)
1. May obtain baseline if Ovarian Cancer high risk

Interpretation (CA 125 level in units/ml)

Normal: CA-125 less than 35 (Does not exclude cancer)
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

Efficacy (ranges are approximate with high values more attributed to post-menopausal patients)

Positive Predictive Value: 35-91%
Negative Predictive Value: 67-90%
Test Specificity
1. Pre-Menopause: 71%
2. Post-Menopause: 93%
Test Sensitivity
1. Pre-Menopause: 61%
2. Post-Menopause: 90%
3. Stage I disease: 50%
4. Advanced disease: 90%

Causes
Increased

Benign Gynecologic Causes
1. Endometriosis
2. Pelvic Inflammatory Disease
3. Uterine Fibroids
4. Pregnancy
5. Menstruation
6. Functional Ovarian Cyst
7. Prior Hysterectomy
8. Post-Menopause
Benign Non-Gynecologic Causes
1. Congestive Heart Failure
2. Liver Cirrhosis
3. Lung disease
4. Myocardial Infarction
5. Obesity
6. Pelvic Irradiation
7. Pancreatitis
8. Recent surgery
9. Tuberculous Peritonitis
Malignant Causes

References