Women’s Health: Does City Life Alter Breast Density?

Epidemiologic studies have found differences between urban and rural women in breast cancer incidence and mortality, both generally being higher in urban areas. Now a British study suggests that women who live or work in urban areas have denser breasts and thus potentially a greater risk of breast cancer, according to a report published online 19 December 2007 ahead of print in Current Medical Research and Opinion. The new findings add to the evidence that breast cancer risk is higher in urban settings and may eventuate in new breast cancer screening guidelines. Breasts are made up of glandular and fatty tissue. Glandular tissue is denser than fatty tissue and harder to read on a mammo-gram; a higher percentage of dense tissue is also linked with increased risk of breast cancer. A meta-analysis of more than 40 studies published in the June 2006 issue of Cancer Epidemiology, Biomarkers & Prevention concluded that women with high breast density have a nearly 5-fold higher breast cancer risk than women with the lowest breast density. The researchers analyzed digital mam-mograms of 972 women, including 318 women from London and 654 women from outside the capital. All the women had received mammography at The Princess Grace Hospital in London. The researchers found that women aged 45–54 who lived in central London were twice as likely to have very dense breasts as women who lived in outlying suburban and rural areas. Age-specific analyses indicated that breast density differences by area were more pronounced in women under age 50. Study leader Nicholas M. Perry, director of the London Breast Institute at The Princess Grace Hospital, was not particularly surprised by the study's findings. While working as a radiologist over a 15-year period , Perry had observed that London women tended to have denser breasts than women living in outlying areas. These personal observations were the main impetus for the study. " Our study was not designed to do anything other than report on the original observation that urban women seemed to have denser breasts, " he says. " Since releasing our findings, I have received numerous comments from radiologists who have observed the same phenomenon. " The biological basis for the new finding remains to be determined. " It may simply be that London women are thinner than women living outside the capital, or it may be due to other factors, " says coauthor Stephen Duffy, an …