Scientists may have found a better way to estimate survival for women with aggressive ovarian cancer, according to a new study by a team of international researchers including those from the Keck School of Medicine of USC.

The findings, which appeared Aug. 17 in the print edition of the journal Annals of Oncology, could focus the development of targeted therapeutic approaches and identify women who might benefit from clinical trials.

An estimated 21,750 American women will be diagnosed with ovarian cancer this year. Average survival for women with the most common and aggressive form is around four years. But survival varies widely between patients, underscoring the need to estimate who is facing a fast-moving or slower disease.

In this study, researchers discovered that a tumor gene test, which is based on tissue removed during cancer surgery, is better at predicting survival among women with ovarian cancer than making estimates the usual way, which is based on a patient’s age and cancer stage.

“We envisioned a test to use at the time of diagnosis — to identify patients unlikely to benefit from current treatments and potentially offer them alternatives,” said Joshua Millstein, PhD, an associate professor of research in preventive medicine at the Keck School and the study’s first author. “For example, those patients might be good candidates for clinical trials or for different treatments that might improve their survival.”

To start, researchers gathered preserved tumor samples and data about duration of survival after diagnosis from nearly 4,000 women worldwide whose information had been collected for previous studies.

They custom-designed a test to measure each sample for the expression of 500 genes linked to the ovarian cancer disease process. Genes “express” proteins and other molecules, based on the gene’s particular DNA, to perform particular functions. They then “trained” the test with a portion of the tumor samples, inputting gene expression data from each tumor as well as the number of years the patient survived after their diagnosis.

Soon, the tumor gene test could accurately predict a patient’s five-year survival rate based on their tumor’s gene expression profile alone. This important information could help newly diagnosed women and their doctors make treatment decisions as well as set targets for developing new therapies.

“Some of the genes we identified as being predictors for good or poor survival may be potential targets for new treatments,” said senior author Susan Ramus, PhD, an ovarian cancer researcher previously at the USC Norris Comprehensive Cancer Center and now a professor at the University of New South Wales in Sydney.

“At the moment, the majority of ovarian cancer patients get the same treatment. It’s not like breast cancer or other cancers where they look at your tumor and select from a range of treatments,” she added. “So this is a way to stratify patients and potentially give more personalized treatment down the track.”

— Leigh Hopper

The research paper involved 125 authors across 86 organizations, including the Keck School. In addition to Millstein, who also is a member of USC Norris, the other Keck School author on the study was Anna Wu, PhD, a professor of preventive medicine who focuses on the epidemiology of cancer.

The study was funded, in part, with grants from the National Institutes of Health (R01CA172404, R01CA168758), the United States Department of Defense Ovarian Cancer Research Program (OC110433), the National Cancer Institute (P30CA014089, P30CA034196, K22 CA193860).