Ovarian cancer screening still gets thumbs down
NEW YORK (Reuters Health) - There is no evidence that getting screened for ovarian cancer helps women beat the dread disease, according to updated recommendations from a U.S. government-backed expert panel.
The U.S. Preventive Services Task Force (USPSTF) said it continues to discourage screening in women at average risk, adding that there is no reason to believe women at higher risk would benefit either.
"There simply is not currently a method of screening (for ovarian cancer) that works," Dr. Virginia Moyer, who chairs the USPSTF, told Reuters Health. "The two most common methods actually result in greater harm than benefit."
A survey earlier this year showed many doctors believe ovarian cancer screening is effective and would offer it to patients. Yet clinical trials show it leads to unnecessary surgeries and doesn't find tumours any earlier than when doctors rely on symptoms.
"There is no major organization anywhere that recommends screening for ovarian cancer," Moyer said. "The interesting thing is that it does get done."
Just over one percent of women will get ovarian cancer at some point in their life, 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.
Screening is typically done either by transvaginal ultrasound or a blood test called CA-125. The blood test costs less than $100, while an ultrasound typically runs a few hundred dollars.
According to the largest clinical trial published so far - known as the Prostate, Lung, Colorectal and Ovarian, or PLCO, trial - women screened annually for ovarian cancer were no less likely to die from the disease than those who didn't get regular screening.
About one in ten screened women had a false positive result, and of those a third had one or both ovaries removed. Overall, screening detected one cancer for every 20 surgeries, the USPSTF notes.
Moyer added that screened women actually appear to have higher death rates than those who aren't screened for ovarian cancer, likely due to the risks of surgery.
She also said the screening tests don't seem to detect tumours any earlier than when doctors rely on symptoms alone.
"The tests that we have are not likely to discover it early enough," Moyer explained. "The likelihood is that this particular cancer, once it is discoverable at all, is pretty aggressive."
Studies show about half of women with ovarian cancer survive five years.
A researcher not involved in the new recommendations criticized them for relying too heavily on the PLCO trial, which had several limitations, including using less-sophisticated screening methods.
The UK and Japan are currently running ovarian cancer screening trials using refined combinations of ultrasound and CA-125 tests, allowing doctors to spot more cancers, according to Edward J. Pavlik who directs the Ovarian Cancer Screening Research Program at the University of Kentucky in Lexington.
"My criticism is mostly of the execution of the PLCO," Pavlik told Reuters Health, not the recommendation itself.
In a large study published last year, Pavlik and colleagues found that women who were screened in their program survived longer with ovarian cancer than women who weren't screened. While that suggests modern screening may spot tumours earlier, it still doesn't prove that it saves any lives.
"We need to continue to study ways to improve the accuracy of ovarian cancer screening in the research setting," Dr. John R. van Nagell, who worked with Pavlik on the study, told Reuters Health.
Referring to low rate at which women with advanced cancer can be cured, Nagell said, "Clearly, we need to do everything possible (including more accurate screening) to facilitate early detection."
Moyer said she is hopeful that genetic markers may one day help identify people who are destined to develop ovarian cancer. If that happens, preventive surgery may be a lifesaver.
"I think genomics is going to get us there," Moyer said.
In the meantime, women should avoid getting screened for the disease, she added. If they are at high risk - for instance by having two or more first or second-degree relatives with the disease or by harbouring BRCA1 and BRCA2 mutations - they may consider genetic counselling.
SOURCE: bit.ly/S4btao U.S. Preventive Services Task Force, September 10, 2012.
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