Women can encounter environmental factors that increase their risk of breast cancer at various periods of their physical development, beginning before birth and extending until menopause.
These non-inherited, or epigenetic, changes in DNA can correlate with risk factors for breast cancer, according to research being presented at the 2007 Annual Meeting of the American Association for Cancer Research.
To study the effects of epigenetic changes in DNA, a team of researchers from Columbia University School of Public Health, led by Mary Beth B. Terry, Ph.D., collected information from former participants of the National Collaborative Perinatal Project born between 1959 and 1966.
"We've been following a birth cohort of women who were all born at Columbia in the late 50s and early 60s," said Terry. "We're interested to find if early life factors are associated with breast cancer susceptibility."
The researchers gathered data on childhood and adult exposures, along with blood samples and mammograms, from 263 women. Terry and her colleagues looked at an epigenetic effect called DNA methylation, whereby DNA is tagged by a molecular "methyl" fragment, which alters activation of the genes. In this instance, the researchers looked at global hypomethylation , aberrant methylation throughout the entirety of a person's DNA.
The researchers found differences in global DNA hypomethylation depending on breast cancer risk factors including racial group, smoking status, and infant and childhood size. "Birth size in particular has been correlated with breast cancer later in life, but nobody really knows why," Terry pointed out. "This is a small pilot study to look at one possible mechanism."