Researchers analyzed data from a national study of nearly 55,000 U.S. women and concluded that those who'd had six to seven symptoms of PTSD - such as being easily startled by common noises or avoiding reminders of the traumatic experience - at some point in their life had twice the risk of ovarian cancer compared to those who never had any PTSD symptoms.
"In light of these findings, we need to understand whether successful treatment of PTSD would reduce this risk, and whether other types of stress are also risk factors for ovarian cancer," said co-author Andrea Roberts, a research scientist at the Harvard T.H. Chan School of Public Health in Boston.
The study also found that these women were at significantly higher risk of the most common and aggressive form of the disease.
Women who'd had four to five PTSD symptoms at some point in their life also had an increased risk of ovarian cancer, but the risk did not reach statistical significance, according to the study.
Studies in animals have shown that stress and stress hormones can accelerate ovarian tumor growth, and that chronic stress is associated with larger and more invasive tumors. A human study found an association between PTSD and ovarian cancer, but it included only seven women with ovarian cancer and PTSD. Like this study, the current research only found an association rather than a cause-and-effect link.
"Ovarian cancer has been called a 'silent killer' because it is difficult to detect in its early stages; therefore identifying more specifically who may be at increased risk for developing the disease is important for prevention or earlier treatment," study co-author Laura Kubzansky, a professor of social and behavioral sciences, said in a Harvard news release.
The findings were published Sept. 5 in the journal Cancer Research.
Ovarian cancer is the fifth leading cause of cancer death in U.S. women.
"Ovarian cancer has relatively few known risk factors -- PTSD and other forms of distress, like depression, may represent a novel direction in ovarian cancer prevention research," said study co-author Shelley Tworoger, associate center director of population science at Moffitt Cancer Center in Tampa, Fla.
"If confirmed in other populations, this could be one factor that doctors could consider when determining if a woman is at high risk of ovarian cancer in the future," Tworoger said in the release.