The generally low sensitivity of CA 125 for FIGO stage I ovarian cancer diagnosis increases for endometrioid histotype
The serum marker CA 125 is still the most widely used biomarker for ovarian cancer (OC) diagnosis in gynecological and oncological setting, but its predictive role in early-stage OC is still debated. The aim of this study was to explore the value of CA 125 in distinguishing between early-stage OC and borderline ovarian tumor (BOT) and to evaluate the accuracy of CA 125 in the detection of early stage OC. A retrospective cohort study was performed at the University Hospital of Bologna (Italy) on 1296 consecutive women suffering from OC or BOT (diagnosed at histology) between 1988-2017. Patients for whom CA 125 level was determined preoperatively were included. The positive cut-off level used was >35 U/mL. Of 910 patients, 192 (21.1%) were diagnosed with BOT and 718 (78.9%) with OC. The sensitivity of CA 125 for stage I OC was 54.4 (95% CI: 45.3-63.3) (51.5 for IA, 54.6 for IB, 58.3 for IC), but it increased to 78.0 (95% CI: 63.7-88.0) for stage II. Interestingly, in stage I OC, CA 125 presented a significantly higher sensitivity for the endometrioid histotype [72.4 (95% CI: 52.5-86.5) vs. 49.0 (95% CI: 38.6-59.4), P=0.026]. The positive likelihood ratio of CA 125 for early-stage OC compared to BOT was 1.29 (95% CI: 1.06-1.58). Despite its limited sensitivity for early-stage OCs, CA 125 still represents a useful serum marker to early differentiate between OCs and BOTs. Its sensitivity for stage I OC increases in endometrioid histotype.