Better ovarian cancer screening, still no answers
New York: After disappointing results earlier this year, researchers say new study findings from Kentucky offer a bit of hope for ovarian cancer screening.
But they still fall short of answering the important question: does ovarian cancer screening save lives?
One in 72 women will get ovarian cancer at some point, usually when they are older, according to the National Cancer Institute. But in most cases symptoms don`t start until the cancer has spread, making the disease harder to treat.
Doctors have hoped that screening women regularly might save lives by catching ovarian cancer earlier. Yet a large trial published in the Journal of the American Medical Association in June found that wasn`t the case.
Now, researchers say the previous disappointment may have been due to problems with the screening method used.
"Maybe some of the existing trials were started a little bit prematurely," said Dr. John Rensselaer van Nagell Jr., who heads the division of gynaecologic oncology at the University of Kentucky Medical Center in Lexington.
For the past quarter century, van Nagell has been part of a study screening thousands of Kentucky women for ovarian cancer. The women were at least 50 years old or had family members with the disease, but none of them had symptoms at the outset of the study.
Out of more than 37,000 screened annually with ultrasound, 76 women had ovarian cancer diagnosed by a biopsy and 47 cases were invasive.
On the other hand, 447 women had a false alarm that ended up not being cancer, while 12 tumors were missed by the screening.
The researchers refined the screening method over time. In the end, one out of every five positive tests turned out to be cancer. Van Nagell said that over the past five years, doctors did an average of five operations per cancer they found.
While that may not sound impressive, an editorial published along with the new findings in the journal Obstetrics and Gynecology notes it`s better than previous studies. One of those studies, published in 2008, found that among more than 78,000 women, ovarian cancer deaths were not reduced when doctors offered a blood test known as CA-125 and ultrasound.
The Kentucky team also found that screened women survived longer after a cancer diagnosis than women who weren`t screened.
Overall, 75 percent of women with invasive cancer detected by screening survived at least five years, compared with just 54 percent of women whose disease was found because they had symptoms.
"The fact is that in Kentucky if you were in this screening trial your survival was significantly higher than if you were from the same geographical area and you weren`t screened," van Nagell said.
An ultrasound costs about $50, he added, whereas treatment for advanced ovarian cancer may be as much as $300,000.
He said more research needs to be done before screening can be broadly recommended. But women with a family history of the disease or genetic susceptibility "might consider trying to become a participant in a screening trial like this," he said.
"Screening as a method to obtain early detection is imperfect, but it is far better than just clinical examination," van Nagell told Reuters Health.
But he acknowledged that in fact his study doesn`t prove that.
One problem is that simply because screening finds cancer earlier, screened patients automatically survive longer with the disease than people who don`t get diagnosed until they notice something is wrong.
As a consequence of this so-called lead-time bias, survival differences don`t necessarily mean screening has prolonged anyone`s life.
What`s more, it`s possible that the volunteers in the Kentucky study may have been healthier to begin with.
In an editorial, Dr. Ian Jacobs and Dr. Usha Menon of University College London note that no report so far has showed ovarian cancer screening saves lives, despite the new findings.
"These figures sound encouraging but simply may reflect a combination of lead time of screen detection and a healthy-volunteer effect rather than an effect on the natural history of ovarian cancer, which will translate to a mortality reduction," they say.
The government-backed U.S. Preventive Services Task Force recommends against routine screening for ovarian cancer.