Social isolation speeds up growth of breast cancer

U.S. researchers found a depressing, socially isolated environment can alter the biology of a disease and speed up the growth of breast cancer, according to media report Wednesday.

The findings, published in the journal Cancer Prevention Research, showed that social isolation can actually change the expression of genes important in the growth of mammary gland tumors.

Researchers at the University of Chicago randomly assigned mice that were genetically susceptible to breast cancer to live either in isolation or in group housing. The mice stressed because they were separated from their mothers developed more and larger mammary gland tumours than more contented animals.

"What we found was the isolated mice developed larger and more breast cancers than the group-housed mice," according to Dr. Suzanne D. Conzen, an associate professor of medicine at the University of Chicago and the study's lead author.

Conzen's team measured gene expression and found changes in the activity of genes that play a role in tumour growth in the stressed animals, suggesting that they may have been directly influenced by surging levels of stress hormones.

The researchers said more work was needed to pin down exactly which cell types are affected.

As to the practical applications of the research, Conzen said the study raised hopes of new ways to block cancer growth.

"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 said.

Dr Caryn Lerman, editor of the journal believed the study used an elegant preclinical model and showed that social isolation alters expression of genes important in mammary gland tumour growth.

Oliver Childs, of the charity Cancer Research UK, cautioned that the findings.　He said: "These experiments were carried out in mice, so certainly do not prove that the stress caused by social isolation causes cancer to get worse in humans.