New Test for Detecting Early-Stage Ovarian Cancer

There is good news for the women who are worried about developing ovarian cancer, in the form of a new test that could catch it in the early stages. The new blood test is able to detect elevated levels of the protein called CA125, and when combined with ultrasound technology it could prove to be an effective screening strategy for finding ovarian cancer in its earliest and most treatable stages.

Researchers have said that the very early findings from the largest randomized ovarian cancer screening study ever conducted are promising. However, it will still be several years until it is clear if this screening method evaluated during the trial will save lives.

Approximately more than 200,000 postmenopausal women who live in the U.K. are participating in this study, which will be complete in 2014. The researcher Usha Menon, M.D. from the University College London, said that the early results from the study show that the screening is feasible.

Ovarian cancer is a highly treatable cancer when it is detected early, with a survival rate of approximately 92 percent at least five years after being diagnosed. However, more than two out of three patients that are diagnosed with the cancer are in the advanced stage of the disease, when the five-year survival rate is only 20 to 30 percent.

According to the American Cancer Society, more than 21,000 new cases of ovarian cancer were diagnosed in the U.S. alone in 2008, and more than 15,000 of the women died from the disease. This is why the stakes are so high for developing an effective early screening strategy.

The CA125 blood test, which was first developed in the early 1980s, measures a protein that is elevated in patients that have ovarian cancer. The second generation of this test has been proven useful for evaluating how well a patient is responding to ovarian cancer treatments. Because of this test's usefulness as a screening tool to detect ovarian cancer, it is more controversial because its false-positive rates tend to be higher, which can lead to unnecessary follow-up testing and surgery.

In the study done in the U.K., the researchers evaluated a new way of using the CA125 blood test, which they hope will prove to be more useful for diagnosing ovarian cancer. Traditionally, a CA125 level of 35 or above has been considered to be elevated and a level of CA125 below this has been considered the normal level. However, in the risk-assessment model that was developed by Menon and colleagues, a woman’s absolute CA125 level is less important than the changes in CA125 from year to year. Age also has to be considered, since the risk for developing ovarian cancer increases with age.

The ongoing study in the U.K. includes 202,638 postmenopausal women that are between the ages of 50 and 74 at recruitment between the years of 2001 and 2005 who were randomly assigned to undergo no screening, annual screening with alone, or annual screening with  the CA125 test and ultrasound for 10 years. Early results from this trial have shown that the CA125 plus ultrasound detected 90 percent of the ovarian cancers identified so far in the combined screening group, while the ultrasound alone identified 75 percent of the cancers that were reported in this screening group.

Almost half of the ovarian cancers detected in both of he screening groups were in the early stages. The total number of the ovarian cancers detected in the two screening groups were similar. However, the combined-screening group had fewer repeat tests and almost nine times fewer surgeries were performed to confirm the diagnosis for every ovarian cancer detected. Approximately thirty-five surgeries were performed to detect one cancer in the ultrasound group alone in comparison to the three surgeries for every cancer detected in the combined screening group.

Robert A. Smith, Ph.D., the Director of Cancer Screening at the American Cancer Society, says that the final results from the trial in the U.K., along with the as yet published results from a study that was conducted by the National Cancer Institute, should reveal more about whether the CA125 test and ultrasound will prove useful for routine screening.

Mr. Smith said, “For two decades we have been exploring ways to effectively use CA125 and ultrasound to screen for ovarian cancer. If these studies conclude that these new methods of using these tools have a favorable benefit-to-harm ratio, routine screening for ovarian cancer may become a reality for postmenopausal women.”