A woman's likelihood of surviving ovarian cancer may be linked to levels of two proteins, researchers have found.

Women with high levels of the proteins had an average survival of 11 years compared with just over 2.6 years for those with low levels of both proteins, the U.S. team reported in Thursday's issue of the New England Journal of Medicine.

In particular, low levels of a protein called Dicer predicted poor outcomes, the researchers found.

"In the long run, this kind of a factor may be useful as a prognostic factor," said the study's senior author, Dr. Anil Sood, a professor in the departments of gynecologic oncology and cancer biology at the university's M.D. Anderson Cancer Center in Houston.

Potentially, the protein levels could be used to guide treatment decisions and attack tumours, Sood added.

The researchers analyzed the makeup of 111 ovarian cancer tumours, which were compared to the patient's clinical outcomes. The findings were supported by a second analysis in a different group of 132 ovarian cancer patients.

Dicer levels were also found to affect survival among people with lung cancer and breast cancer.

Dicer and the other protein, called Drosha, are crucial for types of microRNA interference, which cells use to shut down genes, Sood said.

MicroRNAs regulate processes that are important for aspects of cell growth, and have provided insight into the mechanisms of human cancer, according to a journal editorial accompanying the study.

"Not only does this work provide useful prognostic markers, but also, perhaps these molecular mechanisms predicting outcome are the first steps toward designing strategies to target miRNA-processing mechanisms with the goal of improving outcomes," wrote Frank Slack and Johanne Weidhass of Yale University in New Haven, Conn.

The editorial writers reported holding patents on the use of microRNAS as potential diagnostic markers and cancer treatments. One study author reported receiving consulting fees from drug companies.