Ovarian cancer: 10-year survival is higher than expected

About one-third of ovarian cancer patients survived longer than expected—at least 10 years after diagnosis, according to an epidemiological study published online in the Journal of Obstetrics and Gynecology.

The unexpected result opposes the common notion that women diagnosed with ovarian cancer face a death sentence.

“The perception that almost all women will die of this disease is not correct,” said lead author Rosemary Cress, DrPH, an epidemiologist and associate adjunct professor in the University of California Davis Department of Public Health Sciences, in Davis, CA. “This information will be helpful to physicians who first diagnose these patients and the obstetricians/gynecologists who take care of them after they receive treatment from specialists.”

While the study confirmed certain characteristics associated with ovarian cancer survival—younger age, earlier stage, and lower grade tumors at diagnosis—it also identified a surprising number of long-term survivors who didn’t meet those criteria.

For this retrospective study, Dr. Cress and her colleagues at the UC Davis Comprehensive Cancer Center in Sacramento, CA, used the California Cancer Registry to analyze data reported on all California residents diagnosed with epithelial ovarian cancer (the most common type of ovarian cancer) between 1994 and 2001.

Of the 11,541 patients in the registry database, the researchers found that 3,582 (31%) survived more than 10 years. This was the first research to look at 10-year trajectories for patients; most survival studies have looked only at 5-year survival or less.

Among the long-term survivors, the results showed that the majority were—as expected—younger, had early-stage disease when they were diagnosed, and their tumors were of a lower-risk tissue type. But what the researchers didn’t expect was that 954 of the 3,582 long-term survivors would be high-risk patients because of their tumor stage, grade, or older age at diagnosis.

“This information is important for patient counseling,” said study co-author Gary Leiserowitz, MD, professor of gynecologic oncology and interim chair of the UC Davis Department of Obstetrics and Gynecology. “Many patients and physicians know that ovarian cancer is a dangerous cancer, but they don’t realize that there is significant biological variability among patients. It’s not a uniformly fatal prognosis.”

The next step in the research is to figure out why so many women who are given a poor prognosis eventually beat their odds. “For a disease that is so dangerous, why are so many surviving?” Dr. Leiserowitz asked.

One theory, he said, is that ovarian cancer patients who carry mutations in the tumor suppressor genes BRCA 1 and BRCA 2 respond better to chemotherapy than those who don’t. He also suggested that other biological differences among patients with advanced ovarian cancer may affect individual outcomes. It’s also possible that some patients get more effective treatment than others, boosting their survival odds.

“This is an exploratory study to figure out who has survived,” Dr. Leiserowitz said. “We can now go back and look at tumor tissue to do a comparison between long- and short-term survivors to see if there is a genetic basis for that.”