Clinical relevance of CA125 in low-grade serous ovarian cancer: a retrospective multi-center JAGO/NOGGO study.

OBJECTIVE

This study aimed to assess the association of CA125 levels at pre-defined clinical time points with survival outcomes and to evaluate its role in recurrence detection in low-grade serous ovarian cancer.

METHODS

In this retrospective multi-center cohort study, patients with low-grade serous ovarian cancer of all International Federation of Gynecology and Obstetrics stages treated between 2007 and 2023 at 9 tertiary centers in Germany and Austria were included. Clinical data and serial CA125 measurements were extracted from medical records at pre-defined time points: diagnosis, after debulking surgery, during adjuvant therapy, follow-up, and recurrence. Associations with progression-free survival and overall survival were analyzed using Kaplan-Meier estimates and Cox regression. Sensitivity of CA125 for recurrence detection was assessed.

RESULTS

A total of 368 patients were included; 84.2% had International Federation of Gynecology and Obstetrics stage IIB to IV disease. Median baseline CA125 was 113 U/mL, declining to 16 U/mL after primary treatment and remaining below 35 U/mL during follow-up. A 10-fold increase in baseline CA125 was associated with worse overall survival (hazard ratio 2.24, 95% confidence interval 1.37 to 3.67), remaining significant after adjustment for International Federation of Gynecology and Obstetrics stage, residual disease, age, and ascites (hazard ratio 1.90; 95% confidence interval 1.13 to 3.19). Elevated post-operative CA125 was associated with shorter progression-free survival. Persistently elevated CA125 after 6 cycles of adjuvant chemotherapy was associated with a higher hazard of progression or death (hazard ratio 5.54; 95% confidence interval 2.21 to 13.9). At recurrence, CA125 detected most relapses; however, 15.7% occurred despite normal marker levels, corresponding to a sensitivity of 84% (95% CI 74.0 to 90.4).

CONCLUSIONS

CA125 in low-grade serous ovarian cancer correlates with disease stage, reflects treatment response, and shows prognostic relevance for progression-free survival at pre-defined clinical time points. It may support recurrence detection but should not be used as a stand-alone marker.