“We developed an antibody recognizing the high-molecular-weight protein that’s shed from about 80% of ovarian cancers,” the vice president for Translational Research explains. “It wasn’t designed as a screening test, but rather to follow women with known ovarian cancer and determine their response to treatment and to detect recurrence.”
That didn’t stop ovarian cancer researchers, however. Since Bast's discovery more than 30 years ago, many have studied CA-125’s role in early detection, but with little success.
Both Bast and Karen Lu, M.D., chair of Gynecologic Oncology and Reproductive Medicine, thought a better biomarker, coupled with new technologies, ultimately would trump CA-125. Yet in head-to-head scientific studies, no better marker was found. That finding, together with the CA-125 change-over-time mathematical model, again renewed interest.
Thus the MD Anderson-led study of CA-125 was born. More than 4,000 healthy women are enrolled from seven sites across the country, and more than 20,000 blood samples have been collected. To date, all but one of the ovarian cancers have been found in their earliest, most curable stages.
Such trials take an abundance of resources. Despite MD Anderson’s large Specialized Programs of Research Excellence grant from the National Cancer Institute, which served as seed funding, philanthropic support is paramount to the study’s success, Bast says.
“Without the year-in, year-out generosity from Golfers Against Cancer, the Tracy Jo Wilson Ovarian Cancer Foundation, the Mossy Foundation, the Norton Family, and Stuart and Gaye Lynn Zarrow, in particular, a trial of this scope and size just isn’t possible,” he insists.
Each of the screening sites across the country also depends on local donors.
Time will soon tell if CA-125 finally answers the need for an early ovarian cancer screening tool — the results of the large United Kingdom trial are due in 2015.
“After 32 years, we’ll all be delighted if CA-125 detects ovarian cancer earlier,“ Bast says. “But moving forward, we really need to discover how to accelerate further development of screening tests.”