Changes in Breast Density May Impact Breast Cancer Risk

 Behind the Cancer Headlines®

March 8, 2007 

Changes in breast density within a three year period may impact breast cancer risk, according to a new study published in the Journal of the National Cancer Institute. The two measurements of breast density needed to calculate that change may better predict a woman's risk of breast cancer than a single measurement.  

High breast density is a strong predictor of breast cancer risk, but researchers did not know whether changes in breast density over time would affect this risk. Karla Kerlikowske, M.D., of the University of California, San Francisco, and colleagues looked at breast density data from 301,955 women aged 30 and older who had received at least two mammograms between January 1993 and December 2003. Of those women, 2,639 were diagnosed with breast cancer within 12 months of their last screening.  

An increase in breast density was associated with a greater risk of breast cancer, regardless of the woman's original breast density measurement. Women with lower breast density after their second mammogram had a reduced risk of breast cancer, except for those who were initially in the highest density group.  

"It is not known why some women may have an increase in breast density over time with increasing age," the authors write. "Decreasing weight, increased alcohol intake, or changes in diet or medication may contribute to increasing breast density, and their possible effects on changes in breast density over time warrant further study."

SOURCE: 

Journal of the National Cancer Institute, March 7, 2007