It examines the cellular “ecosystem” around secondary cancers, those in other parts of the body once the cancer has spread from the ovaries.
The test scores depending on whether the tumor spread is in a dominant cell type (giving a low score) or a more diverse cell population containing immune or connective tissue cells (high score).
The scientists found that survival rates were far worse for those women with a high score than for those with a low score.
Only 9% of high-scoring women survived five years of diagnosis, compared with 42% of those whose cancer spread was dominated by one cell type.
The test provides a stronger predictor of poor survival than any other tool in use.
Doctors say it will identify those women who have the most life-threatening disease and who urgently need the most aggressive treatment.
Around 7,000 women are diagnosed with ovarian cancer every year in the UK and the disease kills around 4,000 women a year.
Symptoms may be vague and include feelings of bloating or fullness, irregular periods or bleeding, stomach or back pain, and more frequent urination than normal.
Pain during sex and constipation are other possible signs.
Dr Yinyin Yuan, from the Cancer Research Institute, said: ‘We used to think of tumors as simply a collection of cancer cells, but we now know that they are often complex ecosystems that also consist of different types of healthy cells.
‘Our study revealed that different cell populations at cancer spreading sites are a clinically important feature of particularly aggressive ovarian cancers.
‘We have developed a new test to assess the diversity of metastatic sites and use it to predict a woman’s chances of survival from the disease.
“More work is needed to refine our test and move it to the clinic, but, in the future, it could be used to identify women with particularly aggressive ovarian cancers so they can be treated with the best possible therapies available on the NHS or through clinical studies. “
The research on the test, which involved 61 women with 192 secondary cancers treated at the Sun Yat-sen University Cancer Center in China, was published in the journal Oncotarget.
It was funded by the Cancer Research Institute, the Wellcome Trust and the Royal Marsden Biomedical Research Center.
Professor Paul Workman, chief executive of the Cancer Research Institute, said: ‘Ovarian cancer is more likely to spread than many other cancers because there is no barrier between the ovaries and the peritoneal cavity, the space filled with liquid in our torso which houses the organs of the body.
“It is therefore critical to understand more about the likely progression of the disease among cancers that have spread and to improve in tailoring our treatment to individual women.
“Finding ways to treat highly aggressive ovarian cancers is a huge challenge. But knowing that a woman has a particularly lethal form of the disease, we can try to explore aggressive combination treatments and give women choices about what care they want to receive.”