April 6, 2017

expert reaction to study looking at air pollution and breast density

In a new study publishing in Breast Cancer Research researchers report that living in areas with a high level of fine particles from air pollution may increase a woman’s chance of having dense breasts.

Dr Graham Wheeler, Medical Statistician, Cancer Research UK & UCL Cancer Trials Centre, UCL, said:

“Despite this being a large study, involving nearly 280,000 women, the association between exposure to PM2.5 and increased breast density is not clear-cut because those women with the highest breast density were not associated with higher PM2.5 exposure – so we can’t yet be confident in the overall relationship.  Strangely, women with a breast density of 76% and higher were not associated with having higher PM2.5 exposures than women with a breast density of 25%-50%, but women with a breast density of 51%-75% were.  If higher exposure to PM2.5 were associated with increased breast density, this would not be the case.

“Furthermore, this observational study is a snapshot of breast density based on one mammogram per woman and the average levels of fine particles and ozone in an area, rather than person-specific exposures.  A study with repeated mammograms over time and person-specific readings of air pollution markers would provide a far more accurate picture of the relationship between breast density and air pollution.”

* ‘Association between air pollution and mammographic breast density in the Breast Cancer Surveilance Consortium’ by Lusine Yaghjyan et al. will be published in Breast Cancer Research on Thursday 6 April 2017.

Declared interests

Dr Graham Wheeler: “I am employed by UCL, have a visiting researcher position at the MRC Biostatistics Unit at the University of Cambridge, am a Fellow of the Royal Statistical Society, and a voluntary research committee member for Chiltern Music Therapy, a not-for-profit organisation providing music therapy services. I have no financial conflicts of interest.”