A major trial to detect one of the most elusive and deadly cancers - ovarian - has failed to save lives, after two decades of work.
A major trial to detect one of the most elusive and deadly cancers - ovarian - has failed to save lives, after two decades of work.
The researchers, at University College London, said the results were a disappointment - and thanked the 200,000 people who participated.
The trial had looked promising, with annual blood tests detecting cases of ovarian cancer earlier.
But routine screening for the cancer is now a distant prospect.
Ovarian cancer is tricky to diagnose because the symptoms are easily mistaken for less serious health problems.
They include:
"Some women are diagnosed so late they are too sick to start treatment," the trial's lead investigator, Prof Usha Menon, said.
And two out of every three patients die within a decade of diagnosis.
The UK Collaborative Trial of Ovarian Cancer Screening - the largest in the world - tracked levels of CA125, a chemical released by ovarian tumours, in the blood and sent participants in whom they were rising for an ultrasound scan.
And this led to:
But the final results, published in the Lancet medical journal, showed the screening had failed to save lives.
Prof Menon told BBC News: "I was hoping there'd be something in this - it is disappointing news.
"It is about not giving up at this point - we have suffered a setback and need to get up and march forward again."
There is some evidence the cases detected earlier than usual were still highly aggressive and hard to treat.
And the researchers say they may need to find cancers even earlier and in even more women to affect survival rates.
Scientists hoping to detect ovarian cancer early are now looking at other chemicals in the blood, fragments of DNA released by tumours and exosomes - microscopic fatty spheres break off cancerous cells.
But these would have to go through the same long-term, large-scale trials.
"Realistically, this means we have to reluctantly accept that population screening for ovarian cancer is more than a decade away," Prof Ian Jacobs, from the University of New South Wales, said.
"This is deeply disappointing and frustrating given the hope of all involved that we would save the lives of thousands of women."
About 4,000 people die from ovarian cancer every year in the UK alone.
Cancer Research UK chief executive Michelle Mitchell said people needed to be more aware of the symptoms.
"Symptoms of ovarian cancer can be quite vague [so] whether it's needing to go to the toilet more often, pain, bloating or something else, raise it with your GP," she said.
"In most cases it won't be cancer - but it's best to get it checked out."
By James Gallagher
Health and science correspondent- BBC
