Higher levels of a particular white blood cell is associated with a greater chance of surviving ovarian cancer, an international study has shown.

Predicting a woman's chances of surviving ovarian cancer could be made easier following a discovery by international researchers.

Led by the US Mayo Clinic and UNSW Sydney, they found patients with a high level of white blood cells called tumour infiltrating lymphocytes (TILs) had a greater chance of recovering.

It's hoped the finding will lead to better treatments for the deadly disease.

About 1500 Australian women are diagnosed with ovarian cancer every year and the overall five-year survival rate is just 43 per cent.

Analysis of ovarian tumour tissue samples taken from more than 5500 patients found patients with high-grade ovarian cancer showed the most infiltration with TILs, which were associated with longer overall survival.

The findings of the Ovarian Tumour Tissue Analysis study are published in the journal JAMA Oncology.

Dr Matthew Block, a US oncologist at the Mayo Clinic, says little was known about the role of TILs in fighting high-grade ovarian cancer.

However, this study shows a specific type of TIL has an important role to play in fighting the disease.

"We know that a type of TIL called cytotoxic CD8 is present in the tumours of patients with high-grade ovarian cancer," Dr Block said.

What was important was trying to develop ways to increase the number of those white blood cells, he said.

"Developing a better understanding of factors that increase CD8 TILs will be key to developing treatments to achieve better outcomes in treating patients with high-grade ovarian cancer," Dr Block said.