The primary aim of the study was to validate the recently introduced GCIG (The Gynaecological Cancer Intergroup) simplified CA125 response criteria (Rustin, 2003) in predicting a response by WHO criteria, in the monitoring of second-line chemotherapy in a well-defined group of consecutive patients with epithelial ovarian carcinoma all pretreated with paclitaxel–platinum as first-line chemotherapy. This evidence concerns the gene MUC16 and cancer.