Cancer Epidemiology Biomarkers & Prevention paper also shows that having a baby or nearing menopause reduced the amount of methylation.
Methylation in genes that control breast cancer provides a molecular clock that could one day help researchers more accurately determine a woman’s risk for developing breast cancer and provide a new approach for treatment, report UT Southwestern Medical Center researchers.
Previous studies by the UT team showed that apparently normal breast cells from women with breast cancer had increased methylation of a tumor-suppressor gene called RASSF1A.
In the current work, the scientists sampled cells from 164 women with breast cancer, women at high risk of developing breast cancer, and women with a low risk for the disease. The researchers examined methylation levels of five tumor-suppressor genes. Their findings indicate that methylation of RASSF1A and other genes increases steadily during the years of ovarian cycling up to about age 55.
Interestingly, having children, which is known to reduce breast-cancer risk if it occurs early in life, and getting close to menopause were associated with a reduction in methylation for some genes, according to the investigators.
The study is published in the May 14 issue of Cancer Epidemiology Biomarkers & Prevention.