Abstract
Ovarian cancer can be cured in up to 90% of cases if diagnosed early. CA125, the most studied ovarian cancer biomarker, exhibits poor sensitivity for detecting early disease stages and low specificity to malignancy. RECAF, the alpha-fetoprotein receptor, is a wide-spectrum oncofetal antigen with clinical potential for cancer diagnosis, screening, and monitoring. This study evaluated the performance of RECAF as a diagnostic tool and the sensitivity of a combination of RECAF and CA125 to detect early stages of ovarian cancer at a cutoff resulting in 100% specificity among healthy women. This retrospective case-control study was designed to measure the serum levels of RECAF and CA125 in normal individuals (n=106) and cancer patients stages I/II (RECAF, n=32; CA125, n=35) and III/IV (RECAF, n=49; CA125, n=51). A competitive chemiluminescence assay was developed to measure the circulating RECAF. To eliminate any false positives, we classified as positive any patient with a RECAF or a CA125 value higher than their respective 100% specificity cutoff. We have shown that RECAF discriminated cancer and healthy donors better than CA125, particularly in the early stages (AUC(RECAF)=0.96 and AUC(CA125)=0.805). CA125 sensitivity was lower in the early stages than in the advance stages; RECAF sensitivity was high at all stages. A combination of CA125 and RECAF detected three out of four early-stage patients, with no false positives. In conclusion, the combination of RECAF and CA125 serum values provides the specificity and the sensitivity necessary to screen for ovarian cancer and in particular, to detect early stages of the disease.