Screening Test Evaluated for Early Detection of Ovarian Cancer

A protein that has long been recognized for predicting ovarian cancer recurrence now shows promise as a screening tool for the initial phases of the disease.

The simple blood test could offer a much-needed screening tool to detect ovarian cancer in its early stages, even in the most aggressive forms, in postmenopausal women at average risk for the disease.

Scientists at the MD Anderson Cancer Center (Houston, TX, USA) collaborating with other institutions, enrolled 4,051 women from seven sites across the USA, for a prospective, single-arm, 11-year study. All were healthy, postmenopausal women, ages 50 to 74 years, with no strong family history of breast or ovarian cancer. The study’s primary endpoint was specificity, or few false positives. In addition, the study looked at the positive predictive value, or the number of operations required to detect a case of ovarian cancer.

Each woman received a baseline cancer antigen 125 (CA-125) blood test. The Risk of Ovarian Cancer Algorithm (ROCA) was used as a mathematical model based on the patient’s age and CA-125 score. Women were stratified to one of three risks groups, with the respective follow-up: “low,” came back in a year for a follow-up blood test; “intermediate,” further monitoring with repeat CA-125 blood test in three months; and “high,” referred to receive transvaginal sonography (TVS) and to see a gynecologic oncologist.

The average annual rate of referral to a CA125 test in three months was 5.8%, and the average annual referral rate to TVS and review by a gynecologic oncologist was 0.9%. Ten women underwent surgery on the basis of TVS. Cumulatively, 117 women (2.9%) were determined to be high risk, providing a positive predictive value of 40% for detecting invasive ovarian cancer and the specificity was 99.9%.

Robert C. Bast, MD, the senior author of the study, said, “CA-125 is shed by only 80% of ovarian cancers. At present, we are planning a second trial that will evaluate a panel with four blood tests including CA-125 to detect the cancers we may otherwise miss with CA-125 alone. The current strategy is not perfect, but it appears to be a promising first step.” Prof. Bast, who co-invented the CA-125 assay, has worked closely with Fujirebio Diagnostics, Inc. (Malvern, PA, USA) to develop a clinical laboratory test. The study was published on August 26, 2013, in the journal Cancer.

Related Links:
MD Anderson Cancer Center
Fujirebio Diagnostics