Testing women across the UK for early signs of ovarian cancer - known as the "silent killer"- came a step closer as scientists published results from the largest screening trial ever.
In today's Lancet Oncology, the first analysis of the results of the trial, involving 200,000 women aged 50-74, are published. They bring a national screening programme significantly closer by showing that two separate methods of detecting early-stage cancers work.
However, the full results from the trial will not be available for six more years. "It needs to be seen in the context of what is a 25-year research programme," said project leader Professor Ian Jacobs, director of University College London's institute for women's health.
"It started in the mid-1980s and will finish in 2015. It's a massive, massive effort but all of the results we have got are lining up in the right direction.
"What we need to show everybody is not only that this screening programme can pick up the cancer early, but also that we are saving lives."
Ovarian cancer kills around 4,500 women every year, most of whom only realise they have it in its later stages. Often there are no symptoms, and when there are, they may be confused with something else. They include loss of appetite, indigestion, unexplained weight gain and lower back pain.
Women diagnosed with stage three cancer have a 27% chance of surviving for five years and those in the last phase - stage four - have only a 16% chance.
If ovarian cancer is diagnosed early, women have an 80-90% chance of surviving. Devising a safe and workable screening programme has been the goal of doctors and scientists for decades.
The researchers will not know for certain that screening women prevents deaths until the final data is collected.
The UK leads the world in ovarian cancer screening research, Jacobs said. The study is the biggest randomised trial ever. Two separate screening tests are being compared. One is a blood test which measures the levels of a protein called CA125, which is often higher in women with ovarian cancer. The other is an ultrasound scan that looks for abnormalities in the ovaries.
Half of the women in the study group were screened, 50,000 being given the blood tests and 50,000 given an ultrasound scan, while 100,000 had no screening.
The first screening session picked up ovarian cancers or borderline tumours in 87 women and missed 13 who were diagnosed with ovarian cancer within a year. Almost half of the 58 actual cancers were in the early stages.
There were also false alarms. In the ultrasound group, 845 women had surgery to remove their ovaries because the screening test suggested abnormalities but only 45 of them had ovarian cancer.
