Leslie Kerr at Trent University in Peterborough, Ontario, says the stress of separation from one's mother when young acts as an environmental stress affecting physiology -- probably hormone production -- and increases the risk of developing cancer when exposed to a carcinogen.
"Animals are born and reared in a group, so when they are isolated as an individual it is an environmental stress," Kerr said in a statement.
Trent and colleagues found young mice separated from their mothers for 4 hours daily in the first three weeks of life are not only more likely to develop breast cancer when exposed to a known carcinogen but the cancer develops faster than in mice not subjected to the stress of prolonged maternal separation.
The study, published in Cancer Prevention Research, found carcinogen exposure causing 53 percent of the mice exposed to prolonged separation to develop palpable breast lesions versus 20 percent of mice with brief or no maternal separation.
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