MONDAY, April 16, 2007 (HealthDay News) -- Birth size, race and smoking habits may be associated with epigenetic (non-inherited) changes in DNA that increase the risk of breast cancer, a new study says.
Researchers from the Columbia University School of Public Health analyzed data on childhood and adult environmental exposures -- along with blood samples and mammograms -- from 263 women who were all born at Columbia in the late 1950s and early 1960s.
The study authors focused on an epigenetic effect called DNA methylation, in which the DNA is tagged by a molecular "methyl" fragment that changes the activation of the genes. For this study, the researchers looked at global hypomethylation -- abnormal methylation throughout all of a person's DNA.
The women had differences in global hypomethylation, depending on breast cancer risk factors such as smoking status, race, and their size in infancy and childhood, the study found.
"Birth size in particular has been correlated with breast cancer later in life, but nobody really knows why. This is a small pilot study to look at one possible mechanism," team leader Mary Beth B. Terry said in a prepared statement.
She and her colleagues are currently developing a larger study.
"We're going to try to see if we find these patterns holding up in a much larger sample now. We see this as a first step to understand why measures from birth might be related to adult disease much later in life," Terry said.
The study was to be presented April 15 in Los Angeles at the annual meeting of the American Association for Cancer Research.
The U.S. National Cancer Institute has more about breast cancer risk factors.