Women screened annually for ovarian cancer were just as likely to die from the disease as women who didn't have regular screening, concludes a large new study that found screening did not catch the cancers earlier as it is intended to do.

Calling into question the effectiveness of current ovarian cancer screening techniques, the researchers also found that more of the women screened annually had surgery to remove their ovaries and suffered complications related to false-positive test results -- meaning a screening test suggested they had ovarian cancer when they really didn't.

The finding is in line with other recent research that suggests annual screening doesn't prevent deaths from the disease, which kills most women within 5 years of their diagnosis.

According to the National Cancer Institute, 1 in 72 women will get ovarian cancer. But symptoms usually don't start until the cancer has spread, so most women who are diagnosed already have an advanced stage of the disease that is harder to treat.

Doctors have hoped that screening women regularly could help catch ovarian cancer earlier, when patients have a better long-term outlook.

"We know with ovarian cancer that when the disease is detected in stage 1 you can have 85-90 percent 5-year survival," said Dr. Christine Berg, one of the new study's authors from the National Institutes of Health. "The question is, can you detect the cancers that are destined on to be stage 3 or unfortunately stage 4 at an early enough stage that you can intervene?"

The current study was part of a larger trial looking at the effectiveness of screening for prostate, lung, colorectal and ovarian cancers. Berg and her colleagues randomly split almost 70,000 women into two roughly equal-sized groups -- one that got yearly screening for ovarian cancer between 1993 and 2001, with both blood tests and ultrasounds, and one that didn't.

The researchers then followed women in both groups until 2010, through questionnaires and a national registry of deaths, to see how many were diagnosed with ovarian cancer and how many died of the disease.

Out of about 34,000 women in each group, 212 women in the screening group were diagnosed with ovarian cancer, and 118 of them died from the disease. That compared to 176 diagnoses and 100 deaths in the group that didn't get regular screening.

Also in both groups, more than three-quarters of women who were diagnosed with ovarian cancer already had stage 3 or 4 disease.

The results are published in the Journal of the American Medical Association, and were presented last weekend at the American Society of Clinical Oncology annual meeting in Chicago.
Berg's team also recorded more than 3,000 cases of false-positives in the screening group, and of those, more than 1,000 women who didn't end up having ovarian cancer had surgery to remove an ovary because of a positive test result. Those surgeries resulted in serious complications, including infection or cardiovascular complications, in 163 women.

"Many people will say, 'Oh it's just a blood test, oh it's just an ultrasound, what's the harm?'" Berg told Reuters Health. "The harm is you might have unnecessary surgery that could hurt you."

The combination of blood tests and ultrasounds that her team tested "shouldn't be used for screening in the average-risk woman," she said. "I don't think it's working at all."

Berg said that it's possible that a modified form of the blood test -- which looks for a protein that hints at the presence of ovarian cancer cells - will help doctors identify early cases of ovarian cancer. But she said that researchers need to understand more about how ovarian cancers grow and spread to find the best early detection strategy.

"In the meantime," Berg added, "I think women who are high risk for ovarian cancer based on family history of the disease or a personal history of breast cancer -- they should see a specialist...to consider being tested for genes that predispose to ovarian cancer. But for the normal-risk woman, I don't think we have a screening strategy."

The U.S. Preventive Services Task Force, a federally supported expert panel, also recommends against routine screening for ovarian cancer.