A new genetic discovery could pave the way to earlier diagnosis of ovarian cancer and personalised treatments, scientists claim.
Researchers identified six RNA "messenger" molecules that are found in ovarian cancer cells but not healthy cells.
Spotting the molecules could help diagnose ovarian cancer in its early stages, before it produces any symptoms.
A number of them are also linked to unique proteins that could be targeted with new drugs, according to the researchers.
Messenger RNA (mRNA) is a molecular cousin of DNA that carries information from the genetic code to protein-making machinery in cells.
Lead scientist Dr Christian Barrett, from the University of California at San Diego, US, said: "We were inspired by many studies aimed at using DNA to detect cancer. But we wondered if we could instead develop an ovarian cancer detection test based on tumour-specific mRNA that has disseminated from cancer cells to the cervix and can be collected during a routine Pap (smear) test."
The advantage of using mRNA rather than DNA for diagnosis is that it is much more visible, said the researchers whose findings are reported in the journal Proceedings of the National Academy of Sciences.
A cancer cell might harbour just one or a few copies of a DNA mutation, but mRNA variants can occur in hundreds to thousands of copies per cell.
The findings, made in the laboratory, are just the first step towards developing a method of mRNA diagnosis for ovarian cancer, the researchers pointed out.
Co-author Professor Cheryl Saenz, also from the University of California at San Diego, said: "Clinical trials will need to be conducted on women to confirm the presence of these markers in women that we know have cancer, as well as to document the absence of the markers in women that do not have ovarian cancer."
Each year around 7,100 women in the UK are diagnosed with ovarian cancer.
The disease is often missed until it has reached a late stage, by which time treatment is difficult.