CA-125 still the best marker for ovarian cancer, but better ones are needed

Blood levels of CR-125 protein are still the best predictor of ovarian cancer, but more accurate markers will be necessary if screening is to decrease deaths from the disease, a new study from Brigham and Women’s Hospital concludes.

The study, which was developed to accelerate the process of validating potential ovarian cancer markers, evaluated the performance of 28 serum markers in prediagnostic specimens obtained from asymptomatic women (phase III specimens) compared with the markers’ performance in specimens obtained at diagnosis (phase II) in a different group of women. None of the potential markers performed better than CA-125. The study was developed by the National Cancer Institute’s (NCI) Early Detection Research Network and the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial, which provided the high-quality serum samples used by the researchers.

“CA-125 remains the single best biomarker for ovarian cancer and has its strongest signal within 6 months of diagnosis,” the authors write. “Though disappointing, this conclusion should be viewed in perspective of lessons learned from the study and future directions suggested.”

The researchers note: “[I]f there is hope for reduced mortality for ovarian cancer through screening, we need markers that would show a signal for ovarian cancer more than 6 months remote from diagnosis.” (Performance of all markers except transthyretin declined in phase III specimens obtained more than 6 months from diagnosis.)

Lead investigator Daniel W Cramer, MD, observes that understanding such phenomena as why some women with advanced ovarian cancer have normal CA-125 levels could increase the protein’s usefulness for screening. Although CA-125 is often used to evaluate effectiveness of ovarian cancer treatment, only about half of woman with early stage ovarian cancer have elevated CA-125 blood levels and those levels can rise for reasons other than ovarian cancer.

The research was published in the March issue of Cancer Prevention Research (2011;4[3]:365-374).