Blood test for ovarian cancer saves lives, study finds

A simple blood test for ovarian cancer can save women's lives, a new study finds. Researchers at University College London say their work is the first to demonstrate the effectiveness of screening for the disease. They found that annual blood tests could help reduce women's risk of dying from ovarian cancer by about 20 percent.

The study, published in The Lancet, tracked the health of more than 200,000 post-menopausal women, aged 50 to 74, over a 14-year period. During that time, 1,282 of them were diagnosed with ovarian cancer, and 649 died of the disease.

The women were randomly divided into three groups: some received annual blood tests followed by an ultrasound if results were abnormal; some were screened with annual transvaginal ultrasound exams alone; and a control group received no screening.

When preexisting cases were excluded, women who underwent screening with the blood tests showed significantly lower mortality rates from ovarian cancer as the years went on. In years 7 to 14 of the study, their risk of death from the disease was cut by 20 percent. The researchers plan to follow up for three more years to evaluate the long-term impact of the screening.

"This is the first study ever to show that early detection saves lives, so it's a pretty important finding," CBS News medical contributor Dr. David Agus, director of USC Norris Westside Cancer Center, said on "CBS This Morning."

Agus explained that the researchers tried something different with the blood test than was done in past studies. Rather than just looking for an absolute number in the test results, they used an algorithm to spot changes over time and take other risk factors into consideration.

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CBS News' Dr. Jonathan LaPook reports that this study is encouraging, but researchers caution these women will need to be followed for about another three years before it's clear whether this new method actually works. But given there's no effective screening tool for such a deadly cancer, it is promising.

Ovarian cancer often develops without any obvious symptoms or early warning signs, making an effective screening test especially important.

"Because of where it is in the body, it classically presents later. By the time there's symptoms, it's a big cancer and it's too hard to actually cure," Agus said. "So the death rate of this cancer is pretty high, with only about 45 percent of people living five years after diagnosis."

The Centers for Disease Control and Prevention reports that about 20,000 women in the U.S. are diagnosed with ovarian cancer each year, and about 14,400 die from it.

"If this [screening] were implemented in the United States we would save about 3,500 lives per year," Agus said.

But it may take some time to become widely available. "It's gonna be a debate - do we implement it now because we can save lives potentially, and the risk is there but it's low?" Agus noted that there is also a risk of false positives that could result in some women being put through unnecessary surgery.

"Hopefully this will actually mark what we in the cancer world believe in, which really is prevention and early detection. Because that's going to make the impact," he said.