Stress May Deplete Cancer-Killing Cells
Researchers investigate possible connections

(HealthDay News) -- While a little stress helps keep people focused and motivated, excessive stress can do real health damage, triggering minor concerns including headaches and insomnia, or bringing on more serious problems such as high blood pressure, heart disease and chronic illness.

Now researchers want to add cancer to that list.

According to a study on mice at Johns Hopkins Kimmel Cancer Center, stress may increase the incidence of skin cancer in those at high risk for the disease. Researchers found that mice exposed to stress and to cancer-causing ultraviolet (UV) light developed skin cancer in less than half the time as mice that were not stressed.

Researchers subjected 40 mice to stress by exposing them to the scent of fox urine. The mice also received large amounts of UV light. One of the stressed mice developed a skin tumor within eight weeks of testing. Non-stressed mice exposed to UV light began developing tumors 13 weeks later.

After 21 weeks of testing, 14 of the 40 stressed mice had at least one tumor, compared with two of the non-stressed mice.

"There's a lot of evidence pointing to the negative effects of chronic stress, which dampens our immune system and impacts various aspects of our health," study director Dr. Francisco Tausk, an associate professor of dermatology, said in a prepared statement. "But, to help create solid treatment strategies, we need a better understanding of the mechanisms of how stressors affect skin cancer development."

If these findings in mice prove relevant in humans, stress-reducing activities such as yoga and meditation may help people at high risk for cancer, the researchers suggested.

A preliminary report from an on-going study at the Ohio State University Medical Center suggests similar links between stress and breast cancer patients. The study involves more than 200 women with breast cancer. The women entered the study within one to two weeks of surgical treatment for breast cancer, and before beginning any additional therapy. They were asked to complete questionnaires that identified signs of stress.

Researchers found that the highly stressed women had lower levels of natural killer cells than women who reported less stress. "Natural killer cells have an extremely important function with regard to cancer because they are capable of detecting and killing cancer cells," Dr. Barbara Andersen, leader of the research team and professor of psychology and obstetrics and gynecology at Ohio State University, said in a prepared statement.

"These results, although preliminary, suggest that psychological stress may play a role in how the immune system responds to cancer," Anderson said.

Ohio State researchers want to examine next whether psychological counseling or intervention can reduce stress in these cancer patients and improve immune function. "It's clear from previous research that psychological interventions can improve the quality of life for cancer patients. The question is whether such interventions can have biological or health consequences," Anderson said.

"Psychological interventions might not only have important roles in reducing stress and improving quality of life, but also in extending survival," she added. "We need to examine this possibility more closely."

On the Web

To learn more about stress and disease, visit the National Institutes of Health online.

SOURCES: HealthDay News; Johns Hopkins Medical Institutions, news release; The Ohio State University Medical Center, news release

Author: Laura Wise-Blau
Publication Date: Dec. 31, 2005
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