"Despite the genetic similarity of the mice assigned to grouped versus isolated housing, living in the stressful environment was associated with greater tumor size, suggesting that the social environment may in fact alter the biology of cancer growth then, of course, the question becomes how," she said.

The researchers studied gene expression in the mouse mammary tissues and found that alterations in the expression levels of metabolic pathway genes, which are expected to favor increased tumor growth, had occurred in the isolated mice even before tumor size differences were measurable. These gene expression patterns suggest potential molecular biomarkers and/or targets for preventive intervention in breast cancer.

Further research is needed to focus on which specific cell types the changes in gene expression are taking place, according to Conzen. This knowledge could potentially lead to interventions that block similar pathways favoring the growth of human breast cancer.

"Given the increased knowledge of the human genome we can begin to objectively identify and dissect the specific alterations that take place in cancer-prone tissues of individuals in at-risk environments and that will help us to better understand and implement cancer prevention strategies," she concluded.

aacr/