"We found that exposure to the stress of social isolation leads to reprogramming of genes in fat cells in the mammary glands," said study author Suzanne Conzen, MD, professor of medicine at the University of Chicago. "These fat cells then secrete substances that cause nearby pre-cancerous epithelial cells to proliferate more rapidly, accelerating the development of breast cancer. This local effect of fat cells in the breast was completely unanticipated."
http://www.uchospitals.edu/news/2013/20130618-fat-cells.html (Click link to full story)