Ovarian tumors are often deadly as they are caught too late.
A 14-year study on 200,000 women, published in the Lancet, has been welcomed as a potentially landmark moment in cancer screening.
But the researchers and independent experts say it is still too soon to call for mass screening because of concerns about the analysis.
Ovarian cancer is difficult to pick up as symptoms, including abdominal pain, persistent bloating and difficulty eating, are common in other conditions.
The UK Collaborative Trial of Ovarian Cancer Screening is one of the biggest clinical trials ever conducted and is supposed to give the definitive verdict on screening.
It monitored levels of a chemical called CA125 in women’s blood.
Doctors tracked changes in the levels of CA125, which is produced by ovarian tissue, over time and if levels became elevated then the women were sent for further tests and ultimately surgery.
The results are now in, but the interpretation is a bit messy and the researchers admit it is “controversial”.
Their initial statistical analysis of the data showed no benefit to screening. But there was a benefit when they removed the data from any women who may have already started to develop ovarian tumors.
The researchers then performed a more forgiving statistical analysis, which also showed a benefit.