Aim:  New biomarkers other than carbohydrate antigen (CA) 125 are needed for the detection of ovarian cancer. Osteopontin (OPN) is one of the candidates identified by high‐throughput complementary DNA microarray techniques. We evaluated the preoperative plasma OPN level as a diagnostic biomarker for ovarian cancer in comparison with CA125.

Methods:  Preoperative plasma OPN and CA125 levels were measured and compared in 32 patients with ovarian cancer, 34 patients with benign ovarian tumor, 30 patients with other gynecologic cancers and 31 healthy women. Preoperative plasma OPN levels were also assessed according to tumor stage, the volume of ascites and histological types. The sensitivity and specificity for predicting ovarian cancer was compared between OPN and CA125.

Results:  Preoperative plasma OPN levels were significantly higher in patients with ovarian cancer than in those with benign ovarian tumor, in other gynecologic patients or in healthy women. Stage IV ovarian cancer patients and ovarian cancer patients with ascites had higher plasma OPN levels than those without ascites and in a lower stage. There was no relation between OPN and the histological type. The sensitivity of preoperative plasma OPN in detecting ovarian cancer was 81.3% and almost reached that of CA125. The specificity was moderate. Sensitivity increased to 93.8% with the combination of CA125, compared to 84.4% with CA125 alone.

Conclusion:  Preoperative OPN is a useful biomarker for predicting ovarian cancer. It is especially useful when used complementary to CA125. Larger studies of patients with ovarian cancer showing a low CA125 level or in early stages of ovarian cancer are needed.