C-Mannosyl tryptophan increases in the plasma of patients with ovarian cancer

Ovarian cancer survival is poor, in part, because there are no specific biomarkers for early diagnosis. C-Mannosyl tryptophan (CMW) is a structurally unique glycosylated amino acid recently identified as a novel biomarker of renal dysfunction. The present study investigated whether blood CMW is altered in patients with ovarian cancer and whether differences in blood CMW can distinguish benign from malignant ovarian tumors. Plasma samples were obtained from 49 patients with malignant, borderline or benign ovarian tumors as well as from seven age-matched healthy women. CMW was identified and quantified in these samples using ultra-performance liquid chromatography with fluorometry. Plasma CMW was significantly higher in the malignant tumor group than in the borderline and benign tumor groups, and higher in the combined tumor group (malignant, borderline or benign) compared with healthy controls. Receiver operating characteristic curve analysis of plasma CMW distinguished malignant tumors from borderline/benign tumors [area under the curve (AUC)=0.905]. Discrimination performance was greater than that of cancer antigen (CA) 125 (AUC=0.835), and CMW + CA125 combined achieved even greater discrimination (AUC=0.913, 81.8% sensitivity, 87.5% specificity, 93.1% positive predictive value and 70.0% negative predictive value). Plasma CMW differentiates malignant ovarian cancer from borderline or benign ovarian tumors with high accuracy, and performance is further improved by combined CMW and CA125 measurement.