FRIDAY, Feb. 15 (HealthDay News) -- High levels of daily stress could explain why some women infected with malignancy-linked types of human papillomavirus (HPV) develop cervical cancer, a new study suggests.

Scientists at Fox Chase Cancer Center in Philadelphia tested 74 women, all diagnosed with cervical dysplasia (precancerous cervical lesions), for an immune response to HPV 16, one of the strains of human papillomavirus thought to be a major cause of cervical cancer. The women also completed a questionnaire that assessed stressful life events experienced during the previous six months -- including deaths of family members, loss of a job or divorce -- as well as their perceived daily stress level over the previous month.

The research, published in the February issue of Annals of Behavioral Medicine, found that slightly more than 55 percent of the women tested positive for one or more types of HPV, a sexually transmitted infection that can cause genital warts as well as cancer.

"We observed that stress was associated with deficits in immune response to HPV 16," said Carolyn Y. Fang, the study's lead investigator.

Most HPV infections in healthy women disappear over time without progressing to precancerous cervical lesions or cancer. "That means HPV infection alone is not sufficient to cause cervical cancer," Fang said. "Our study suggests a potential mechanism by which stress may influence cervical disease progression.

"We were surprised to discover no significant association between the occurrence of major stressful life events and immune response to HPV 16, possibly because of the amount of time that had passed since the event and how the women coped," she added. "However, women with higher perceived levels of daily stress were more likely to have an impaired immune response."

HPV expert Dr. Kevin Ault, associate professor of gynecology and obstetrics at Emory University School of Medicine in Atlanta, said, "It is unusual to see psychology and immunology in the same study, and this is very interesting. It is clear that almost all sexually active men and women get infected by HPV but very few have cancer. We already knew that nutrition may play a role. It seems likely that immune responses to HPV are influenced by stress, too."

Dr. Charles Raison, clinical director of Emory University's Mind-Body Program, said the new study adds to the growing evidence that stress can negatively influence health.

"There is data that stress can put the immune system at a disadvantage in dealing with viral infections. Even daily hassles like commuting in bad traffic can impact how the body functions," he said. "If a person with HPV is feeling stressed, it is important to do something positive to reduce the stress load. Exercise is known to help, and psychiatric therapy for any depression is important, too."

Fang added: "We want women to understand that stress does not cause cervical cancer, and feeling stressed out does not mean that one will develop cervical cancer. In this initial study, we observed that stress was associated with deficits in immune response to HPV. Whether stress causes these deficits, however, is unknown, and much more research will need to be done."

To that end, Fang and her research team have launched a five-year randomized trial to examine whether participation in an eight-week stress reduction program can lead to enhanced HPV-specific immune responses in women diagnosed with cervical dysplasia.

U.S. Centers for Disease Control and Prevention statistics show that one in four American women between the ages of 14 and 59 years is infected with HPV. Gardasil, a vaccine that protects against several cancer-causing HPV sub-types, has been approved by the U.S. Food and Drug Administration. However, the vaccine works best when given to girls before they become sexually active and is not effective in women already infected.

That means the best protection against cervical cancer for sexually active women, whether or not diagnosed with HPV, is to have regular Pap tests and to develop good health habits, Ault said.

More information

For more on HPV and cervical cancer, visit the CDC.