What serum levels should be monitored in someone with a history of epithelial ovarian cancer?

Monitoring Serum Levels in Epithelial Ovarian Cancer

Serum CA125 should be monitored regularly in patients with a history of epithelial ovarian cancer, as it can accurately predict tumor relapse with high sensitivity and should be performed at each follow-up visit. 1

Primary Serum Markers for Monitoring

CA125 Monitoring

• CA125 is the primary serum marker for monitoring epithelial ovarian cancer patients 1
• During follow-up after treatment:
  • CA125 should be measured at every follow-up visit 1
  • Follow-up schedule: every 3 months for 2 years, every 4 months during the third year, and every 6 months during years 4 and 5 1
• During chemotherapy:
  • CA125 should be measured before each cycle of chemotherapy 1
  • Levels correlate with tumor response and survival 1
  • A final measurement should be taken one month after the last course 1

Additional Markers for Specific Histological Types

• For mucinous or endometrioid tumors where CA125 may not be elevated:
  • CEA (carcinoembryonic antigen) 1
  • CA19-9 1
• These additional markers should only be measured if CA125 is not elevated at diagnosis 1

Clinical Utility of CA125 Monitoring

Advantages

• High predictive value for recurrence:
  • Sensitivity of 85% during follow-up 1
  • Can predict tumor relapse with a median lead time of 3-3.5 months before clinical detection 2, 3
  • Positive predictive value of 90-100% for clinical progression following CA125 progression 4

Limitations

• Only elevated in approximately 50% of early-stage (FIGO stage I) disease 1
• Elevated in about 85% of advanced disease 1
• Not specific to ovarian cancer; can be elevated in:
  • Non-gynecological malignancies (breast, lung, colon, pancreatic cancer) 1
  • Benign conditions (endometriosis, pelvic inflammatory disease, ovarian cysts) 1
• May not detect small tumor nodules (<2 cm) 3

Imaging in Conjunction with CA125

• CT scans should be performed if there is clinical or CA125 evidence of progressive disease 1
• For patients with abnormal CT scans at baseline:
  • Repeat CT after cycle 6 of chemotherapy 1
  • Earlier CT is indicated if CA125 levels are not falling 1
• FDG-PET-CT scans may be superior to CT scans in detecting small volume operable relapses 1

Prognostic Value of CA125

• Preoperative CA125 levels have prognostic significance for overall survival 5
• The best cut-off for prognostic classification is 70 U/ml 5
• Patients with elevated CA125 (≥35 U/ml) at second-look operations have a 60% chance of clinical recurrence within 4 months 2

Common Pitfalls and Caveats

• Relying solely on CA125 without clinical correlation can lead to premature or delayed intervention
• False positives can occur due to benign conditions affecting the peritoneum 1
• False negatives can occur with small volume disease 3
• CA125 monitoring has inherent limitations in terms of accuracy, with false negative rates ranging from 45% to 70% 4
• Despite its value in detecting recurrence, it remains unknown whether early detection of recurrence by CA125 offers any survival advantage 1

By following these monitoring guidelines, clinicians can optimize the surveillance of patients with epithelial ovarian cancer, potentially leading to earlier detection of recurrence and more timely intervention.