CA-125: A Biomarker Put to the Test

Extract

In 1998, an e-mail beseeching women to undergo annual CA-125 screening for ovarian cancer spread across the Internet. “Please, please, p-l-e-a-s-e tell all your female friends and relatives to insist on a CA-125 blood test every year as part of their annual physical exams,” pleaded the note from a cancer patient. “Don’t take no for an answer.”

Unfortunately, the science behind CA-125 screening wasn’t ready for prime time then, and it still isn’t. In June, a National Cancer Institute–sponsored randomized study published its long-awaited results in the Journal of the American Medical Association . The findings showed that simultaneous CA-125 and vaginal ultrasound screening did not affect ovarian cancer mortality. But this study—the Prostate, Lung, Colorectal, and Ovarian (PLCO) cancer screening trial, launched in 1993—used what some scientists say is an outmoded approach for tumor detection.

Meanwhile, a different study, the UK Collaborative Trial of Ovarian Cancer Screening (UKCTOCS), is using a different screening approach that could be more promising, according to Ian Jacobs, director of the Manchester Academic Health Science Centre, in Manchester, United Kingdom, and one of the study's principal investigators. Thus CA-125 screening, which some still see as perhaps the best hope for early ovarian cancer detection, remains in limbo.