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Stress, Obesity Impact Breast Cancer Risk, Study Suggests

Social Isolation/Breast Cancer

Research reported during the 2011 American Association for Cancer Research Annual Meeting suggests that social isolation is a potent stressor and initiates a strong central nervous system response.

August 9, 2011 – Stress from social isolation combined with a high-fat diet increased levels of a brain neurotransmitter that promotes obesity, insulin resistance and breast cancer risk in a study using mice, say researchers at Georgetown Lombardi Comprehensive Cancer Center.

The findings of the study, funded by the National Cancer Institute, were reported at the 2011 American Association for Cancer Research (AACR) Annual Meeting. Lombardi is part of the Georgetown University Medical Center (GUMC).

Major increases in the level of a neurotransmitter known as NPY were also noted when the mice were isolated and given a high-fat diet. But the mice that were isolated for two weeks and fed a control diet also had elevated neurotransmitter levels and increased terminal end buds, a structure in the mammary gland where breast cancers form.

Suspected Role

Leena Hilakivi-Clarke

Oncology professor Leena Hilakivi-Clarke is senior investigator on the study that links social isolation to obesity and breast cancer risks.

The researchers say their findings appear to link to a number of findings in humans, such as the fact that social isolation is associated with an increased risk of cancer development and mortality, and that obesity is a risk factor for breast cancer.”

“We suspect that NPY may play a role in development of human breast cancer, but we have no evidence for such a connection because no human studies have yet been done,” says the study’s lead investigator, Allison Sumis, a Ph.D. student in GUMC’s tumor biology program.

Lab Results

“We do know that NPY has been shown to increase growth of human breast cancer cells in the laboratory,” she adds. Sumis works with Leena Hilakivi-Clarke, co-director of the Division of Molecular Endocrinology, Nutrition and Obesity at GUMC and the study’s senior investigator.

Sumis adds that the tumors that developed in the high-fat, socially isolated mice appeared earlier and were larger than in the other groups.

“We have yet to translate these findings to humans, but it does suggest that social isolation is a potent stressor and initiates a robust central nervous system response,” she says. “Others have found that a majority of women gain weight after a diagnosis of breast cancer, and it seems likely that stress, even if it is not from social isolation, may play a role.”

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