Do CA125 response criteria overestimate tumour response in second-line treatment of epithelial ovarian carcinoma?

Recent studies indicate that cancer antigen 125 (CA125) response criteria tend to overestimate a tumour reduction measured by standard WHO response criteria in recurrent epithelial ovarian carcinoma. The aim of the study was to validate the recently introduced GCIG (The Gynaecological Cancer Intergroup) CA125 response criteria in predicting a tumour response measured by WHO (World Health Organization) criteria. Changes in CA125 levels (GCIG criteria) were retrospectively compared with alterations in the tumour load (WHO criteria) during second-line chemotherapy with topotecan or paclitaxel–platinum in 124 consecutive patients with recurrent or refractory disease. In patients assessable by both response criteria (n=72), the overall response rate using GCIG CA125 criteria was 57% (95% confidence interval (CI): 45–69%) and significantly higher than the response rate of 39% (95% CI: 28–51%) using WHO response criteria (P=0.045). The GCIG CA125 criteria had a sensitivity of 96% (95% CI: 82–100%), a specificity of 68% (95% CI: 52–81%) and an accuracy of 79% (95% CI: 68–88%) in predicting a response measured by WHO criteria. In conclusion, the GCIG CA125 response criteria seem to overestimate a tumour response by WHO criteria when monitoring the efficacy of second-line chemotherapy with topotecan or paclitaxel–platinum in patients with epithelial ovarian carcinoma.