Is CA125 (Cancer Antigen 125) a reliable marker for ovarian cancer during pregnancy?

CA125 is Not Reliable for Ovarian Cancer Detection During Pregnancy

CA125 is not an accurate marker for ovarian cancer during pregnancy due to physiologic elevations that occur, particularly in the first trimester, limiting its diagnostic utility. 1

CA125 Levels During Normal Pregnancy

• CA125 elevations are expected beginning in the first trimester with reported mean values ranging from 19-85 U/mL and maximum values up to 550 U/mL 1
• Second and third trimester levels typically decrease but can remain elevated in some healthy pregnant women:
  • Maximum reported value of 73 U/mL in second trimester
  • Maximum reported value of 2,420 U/mL in third trimester 1
• First trimester shows significant elevation compared to non-pregnant women under 49 years of age 2

Limitations of CA125 in Pregnancy

• Wide fluctuations in CA125 levels occur during early pregnancy and immediate postpartum period, making clinical correlation difficult 1
• False-positive results are common in pregnancy due to:
  • Normal physiologic changes of pregnancy 2
  • Peritoneal inflammation 1
  • Hormonal changes affecting reproductive organs 3
• Approximately 24% of pregnant women have elevated CA125 levels (>35 U/mL) without cancer 3

Alternative Diagnostic Approaches for Adnexal Masses in Pregnancy

Given the limitations of CA125, other diagnostic modalities should be prioritized:

1. Ultrasound imaging is the primary modality for evaluating adnexal masses in pregnancy:

   • Transvaginal and transabdominal ultrasound with color/power Doppler 1
   • IOTA Simple Rules have better performance than CA125 with sensitivity of 92% and specificity of 69% for predicting malignancy in pregnancy 1

2. MRI without gadolinium is recommended as a secondary imaging modality when:

   • Ultrasound findings are inconclusive
   • Characterization of large masses is needed
   • Assessment of disease extent is required 1

3. Other tumor markers that remain within normal limits during pregnancy may be more useful:

   • CEA, inhibin B, antimüllerian hormone, and LDH 1
   • Alpha-fetoprotein (extremely elevated values >10,000 ng/mL should raise concern for germ cell tumors) 1

Clinical Approach to Suspected Ovarian Cancer in Pregnancy

1. Begin with detailed ultrasound assessment using validated scoring systems for pregnancy:

   • Sassone (sensitivity 69%, specificity 85%)
   • Lerner (sensitivity 77%, specificity 69%)
   • IOTA Simple Rules (sensitivity 92%, specificity 69%) 1

2. If ultrasound suggests malignancy or is indeterminate, proceed to MRI without contrast 1

3. If malignancy is strongly suspected or confirmed, CA125 trends (rather than absolute values) may provide some value for monitoring 1

4. Consider other tumor markers that remain reliable during pregnancy (CEA, inhibin B, antimüllerian hormone) 1

Conclusion

CA125 has significant limitations as a tumor marker during pregnancy due to physiologic elevations that occur naturally, particularly in the first trimester. Ultrasound imaging with validated scoring systems provides superior diagnostic performance for detecting ovarian malignancy in pregnant women.