Being Alone and Stressed May Increase Breast Cancer Risk

Social isolation combined with stressful situations raised odds of disease in animal study

WEDNESDAY, Dec. 9, 2009 (HealthDay News) -- Social isolation and stress may increase breast cancer risk, new research has found.

In a study of rats by University of Chicago researchers, social isolation and stress was associated with a 3.3-fold greater chance of developing breast cancer. The findings also showed that rats kept alone had a 135 percent increase in the number of tumors and a more than 8,000 percent increase in tumor size.

Being isolated and exposed to stressful situations, such as the smell of a predator or being briefly constrained, increased production of the stress hormone corticosterone in the animals, the study authors noted. Isolated rats took longer to recover from a stressful situation than rats living in small groups.

The findings, published online in the early edition of the journal Proceedings of the National Academy of Sciences for the week of Dec. 7 to 13, suggest that isolation and stress could play a role in human breast cancer risk, said Martha McClintock, a professor of psychology and comparative human development at the University of Chicago.

The researchers also have found that women living in high-crime areas face a number of stressors, including social isolation. They noted that black American women have been found to develop breast cancer at an earlier age, although total incidence is similar to that of women in other racial/ethnic groups.

"We need to use these findings to identify the potential targets for intervention to reduce cancer and its psychological and social risk factors," McClintock said in a university news release. "In order to do that, we need to look at the problem from a variety of perspectives, including examining the sources of stress in neighborhoods as well as the biological aspects of cancer development."

More information

The U.S. National Cancer Institute has more about breast cancer risk.

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