A new screening test can detect twice as many cases of ovarian cancer as conventional methods, and could enable faster intervention before the disease reaches advanced stages, new research suggests.

Ovarian cancer is the seventh most common cancer in women globally, and has non-specific symptoms, such as bloating or bowel trouble. This means the disease often reaches an advanced stage by the time of diagnosis, placing survival rates after five years of treatment between 30 and 40 percent.

The new screening test measures the amount of a protein in the blood known as CA125, which previous research has linked to the devleopment of ovarian cancer.

It uses an algorithm to measure variations in this biomarker over time to determine risk factors for the disease, and according to researchers, is more accurate than existing blood tests that evaluate cancer risk based on a fixed threshold of how much CA125 is in the blood.

The team says their new method can detect ovarian cancer in up to 86 percent of women before they demonstrate symptoms, reports Nicky Phillips from The Sydney Morning Herald.

"The sensitivity is very, very high - much higher than people thought would be possible," lead researcher and cancer surgeon Ian Jacobs, who is now the Vice-Chancellor of the University of New South Wales in Australia, told Phillips.

The team, led by scientists from the University College London in the UK, carried out a 14-year randomised control trial, which began with the recruitment of 202,638 post-menopausal women over the age of 50.

They were randomly split into three groups - one was screened using the new statistical test, another was screened using a vaginal ultrasound, and the third group wasn't screened at all.

"It's one of the largest randomised trials ever performed in the history of medicine," Jacobs told The Sydney Morning Herald.

Of the original cohort, 46,232 trial participants continued to have regular screening checks. Their blood was tested once a year for CA125 levels, and the researchers' algorithm predicted risk of ovarian cancer based on factors such as age and the changing levels of the protein.

A portion of the team's results, highlighting the effectiveness of their new screening tool, has been published in the Journal of Clinical Oncology. Results indicating the effectiveness of the ultrasound screenings are expected in June.

"There is currently no national screening program for ovarian cancer [in the UK], as research to date has been unable to provide enough evidence that any one method would improve early detection of tumours," gynaecologist and trial coordinator Usha Menon, from University College London in the UK, told The Guardian.

"These results are therefore very encouraging. They show that use of an early detection strategy based on an individual's CA125 profile significantly improved cancer detection compared to what we've seen in previous screening trials."

Scientists discovered the protein CA125 was linked to ovarian cancer back in the 1980s, but typically classified women as having a greater risk factor if they had amounts of the protein exceeding a certain threshold. But that's not a guarantee: some women with high levels of the protein don't end up with cancer, while some women with low levels do.

"Our findings indicate that this can be an accurate and sensitive screening tool, when used in the context of a woman's pattern of CA125 over time. What's normal for one woman may not be so for another. It is the change in levels of this protein that's important," Jacobs told The Guardian.

If the results in June confirm that the test is more effective than the vaginal ultrasound, and other current screening methods, it could be adopted on a wider scale. This is good news, as earlier diagnoses and faster intervention will inevitably lead to greater survival rates for people affected by this disease. 

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