Can endometriosis elevate Cancer Antigen 125 (CA125) levels?

Endometriosis and CA125 Elevation

Yes, endometriosis can significantly elevate CA125 levels, particularly in advanced cases with deep infiltrating lesions or ovarian endometriomas, while superficial endometriosis typically does not cause significant CA125 elevation. 1

Relationship Between Endometriosis and CA125

• Women with endometriosis display higher mean serum CA125 levels compared to disease-free controls (50.1 ± 62.4 U/mL vs 22.5 ± 25.2 U/mL) 1
• CA125 levels are significantly increased in women with ovarian endometriomas (60.8 ± 63.5 U/mL) and deep infiltrating endometriosis (55.2 ± 68.7 U/mL) compared to women with superficial endometriosis (23.2 ± 24.5 U/mL) 1
• There is no significant difference in CA125 levels between patients with superficial peritoneal lesions and controls without endometriosis 1

Clinical Significance in Diagnosis

• CA125 serum levels correlate with endometriosis severity, with higher levels associated with more severe and extended deep infiltrating endometriosis lesions 1
• Elevated CA125 is a helpful additional parameter to diagnose "endometriotic disease" (deep endometriosis and cystic ovarian endometriosis) in patients with chronic pelvic pain 2
• Following treatment of endometriosis, persistently elevated CA125 levels could suggest incomplete treatment or disease recurrence 2

Important Considerations for Interpretation

• An elevated CA125 in a premenopausal patient with clinical features suggesting endometriosis should not unnecessarily elevate concern for malignancy 3
• CA125 has limited specificity as it can be elevated in various benign conditions including endometriosis, adenomyosis, pelvic inflammatory disease, menstruation, and other benign cysts 4, 5
• Normal physiological variations occur in CA125 levels, with slight increases at ovulation and significant increases during menstruation 2

Clinical Application

• When evaluating adnexal masses, the O-RADS risk stratification system recognizes that tumor marker evaluation should be individualized, acknowledging that endometriosis can cause CA125 elevation that might otherwise suggest malignancy 3
• For ovarian cancer surveillance, clinicians should be aware that elevated CA125 levels may be due to other conditions including endometriosis rather than cancer recurrence 3
• The sensitivity and specificity of CA125 for detecting endometriosis have improved slightly with newer assays, but it remains suboptimal as a standalone diagnostic test for endometriosis 6

Pitfalls to Avoid

• Do not rely solely on CA125 levels to diagnose endometriosis; imaging and clinical findings remain essential 2
• Avoid overinterpreting elevated CA125 in premenopausal women as indicative of malignancy without considering endometriosis as a potential cause 3
• Remember that superficial endometriosis may not cause CA125 elevation, so normal levels do not exclude all forms of endometriosis 1