Blood test detects early-stage ovarian cancer

HOUSTON – Evaluating its change over time, CA-125, the protein long-recognized for predicting ovarian cancer recurrence, now shows promise as a screening tool for early-stage disease, according to researchers at The University of Texas MD Anderson Cancer Center.

The updated findings are published in Cancer; preliminary data were first presented at the 2010 American Society of Clinical Oncology (ASCO) annual meeting. If a larger study shows survival benefit, 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 post-menopausal women at average risk for the disease.

MD Anderson has a long history in the research of the important biomarker. In the 1980s, Robert Bast, M.D., vice president for translational research at MD Anderson and co-investigator on the ASCO study, discovered CA-125 and its predictive value of ovarian cancer recurrence. Since then, researchers at MD Anderson and beyond have been trying to determine its role in early disease detection. The marker, however, can become elevated for reasons other than ovarian cancer, leading to false positives in early screening.

“Over the last ten years, there’s been a lot of excitement over new markers and technologies in ovarian cancer,” said Karen Lu, MD, professor and chair, Department of Gynecologic Oncology and the study’s corresponding author. “I and other scientists in the gynecologic oncology community thought we would ultimately find a better marker than CA-125 for the early detection of the disease. After looking at new markers and testing them head-to-head in strong, scientific studies, we found no marker better than CA-125.”

According to the American Cancer Society, 22,240 women will be diagnosed with ovarian cancer in 2013 and another 14,030 are expected to die from the disease. The challenge, explained Lu, is that more than 70% of women with ovarian cancer are diagnosed with advanced disease.

“Finding a screening mechanism would be the Holy Grail in the fight against ovarian cancer, because when caught early it is not just treatable, but curable,” said Lu, also the trial’s principal investigator.

For the prospective, single-arm, 11-year study, 4,051 women were enrolled from seven sites across the country, with MD Anderson serving as the lead site. All were healthy, post-menopausal women, ages 50-74, 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 CA-125 blood-test. Using the Risk of Ovarian Cancer Algorithm (ROCA), 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.

Based on the women’s CA-125 change over time, the average annual rate of referral to the intermediate and high groups were 5.8% and 0.9%, respectively. Cumulatively, 85 women (2.9%) were determined to be high risk, and thereby received the TVS and wereSuperStar SlipOn