Mammographic Breast Density and Urbanization: Interactions with BMI, Environmental, Lifestyle, and Other Patient Factors.

Nick Perry,Stephen Duffy,Sue Milner,Kefah Mokbel,Hendrik-Tobias Arkenau,Charlotte Lemech,Katja Pinker,Sue Moss,Steve Dixon

doi:10.3390/diagnostics10060418

Abstract

Mammographic breast density (MBD) is an important imaging biomarker of breast cancer risk, but it has been suggested that increased MBD is not a genuine finding once corrected for age and body mass index (BMI). This study examined the association of various factors, including both residing in and working in the urban setting, with MBD. Questionnaires were completed by 1144 women attending for mammography at the London Breast Institute in 2012–2013. Breast density was assessed with an automated volumetric breast density measurement system (Volpara) and compared with subjective radiologist assessment. Multivariable linear regression was used to model the relationship between MBD and residence in the urban setting as well as working in the urban setting, adjusting for both age and BMI and other menstrual, reproductive, and lifestyle factors. Urban residence was significantly associated with an increasing percent of MBD, but this association became non-significant when adjusted for age and BMI. This was not the case for women who were both residents in the urban setting and still working. Our results suggest that the association between urban women and increased MBD can be partially explained by their lower BMI, but for women still working, there appear to be other contributing factors.

Highlights

Mammographic breast density (MBD) has been recognized as an independent biomarker of breast cancer risk, with risk prediction of relevance to both primary and secondary prevention [1,2]
MBD is known to decrease with increasing age and body mass index (BMI) [5,6], and adjusting for these is important in studies of breast cancer risk and models of risk prediction based on mammographic density
Our study found that being an urban resident was associated with increased percent MBD, but this association was not significant after adjustment for age and BMI

Summary

Introduction

Mammographic breast density (MBD) has been recognized as an independent biomarker of breast cancer risk, with risk prediction of relevance to both primary and secondary prevention [1,2]. MBD is influenced significantly by age and body mass index (BMI) [5,6] and adjusting for these factors is important in studies of risk factors for breast cancer [7]. Some studies have shown an association of urban residence with increased breast density [10,11,12]. It has been hypothesized that this is due to lifestyle and environmental factors [10,12], and is associated with an increased risk of breast cancer with exposure to fossil fuel emissions and traffic fumes, which are said to have a weak estrogenic effect but may be inhaled in large volumes [13,14,15,16]

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