Social isolation and related stress could be a factor in increasing human breast cancer risk, says a study.
Researchers at the University of Chicago based their study on a rat model to identify environmental mechanisms contributing to cancer risk.
Lead author Gretchen Hermes, a former researcher at the University and now a resident in psychiatry at the Yale University School of Medicine, found that isolation and stress result in a 3.3-fold increase in the risk of developing cancer among rats with naturally occurring mammary tumors.
Martha McClintock, a psychologist at the University of Chicago and an author of the paper, said: "We need to use these findings to identify potential targets for intervention to reduce cancer and other and its psychological and social risk factors.
"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."
Boffins also found that rats living in isolation experienced a 135 percent increase in the number of tumors and a more than 8,000 percent increase in their size.
The impact of isolation was much larger than the impact another environmental source of tumor formation-the unlimited availability of high-energy food.
The paper, "Social Isolation Dysregulates Endocrine and Behavioral Stress While Increasing Malignant Burden of Spontaneous Mammary Tumors," was published in the Proceedings of the National Academy of Sciences.