Objective Prediction of post-operative residual disease after ovarian cancer cytoreductive surgery remains a topic of interest to gynecologic oncologists. The aim of this study was to explore the correlation between serum CA125, peritoneal cancer index, and intra-operative mapping of ovarian cancer and their predictive value for post-operative outcome.

Methods A total of 70 patients with primary epithelial ovarian cancer, who underwent primary cytoreductive surgery at Charité, Berlin between January 2013 and February 2014 were included. In all patients, pre-operative CA125 values, intra-operative peritoneal cancer index, and intra-operative mapping of ovarian cancer were determined.

Results Using a receiver operating characteristic analysis, cut-off values for CA125, peritoneal cancer index, and intra-operative mapping of ovarian cancer score could be defined. Patients with pre-operative serum CA125 >600 U/mL had a three times higher risk for residual tumor after primary cytoreductive surgery (p=0.037). A peritoneal cancer index score >20 indicated a nine times increased risk for residual tumor (p=0.003). More than six affected abdominopelvic fields on the intra-operative mapping of ovarian cancer was associated with a 25 times higher risk of residual tumor after primary cytoreductive surgery (p≤0.05). The combination of all three values predicted residual tumor in up to 90% of patients.

Conclusion We found that pre-operative CA125 >600 U/mL, peritoneal cancer index >20, and intra-operative mapping of ovarian cancer score >6 could be used as predictors of complete tumor resection. The combination of all these three values predicted the incomplete resection of disease in up to 90% of patients even in experienced centers.