Breast cancer risk factors and a novel measure of volumetric breast density: cross-sectional study

Abstract

We conducted a cross-sectional study nested within a prospective cohort of breast cancer risk factors and two novel measures of breast density volume among 590 women who had attended Glasgow University (1948 -1968), replied to a postal questionnaire (2001) and attended breast screening in Scotland (1989Scotland ( -2002. Volumetric breast density was estimated using a fully automated computer programme applied to digitised film-screen mammograms, from medio-lateral oblique mammograms at the first-screening visit. This measured the proportion of the breast volume composed of dense (non-fatty) tissue (Standard Mammogram Form (SMF)%) and the absolute volume of this tissue (SMF volume, cm 3 ). Median age at first screening was 54.1 years (range: 40.0 -71.5), median SMF volume 70.25 cm 3 (interquartile range: 51.0 -103.0) and mean SMF% 26.3%, s.d. ¼ 8.0% (range: 12.7 -58.8%). Age-adjusted logistic regression models showed a positive relationship between age at last menstrual period and SMF%, odds ratio (OR) per year later: 1.05 (95% confidence interval: 1.01 -1.08, P ¼ 0.004). Number of pregnancies was inversely related to SMF volume, OR per extra pregnancy: 0.78 (0.70 -0.86, Po0.001). There was a suggestion of a quadratic relationship between birthweight and SMF%, with lowest risks in women born under 2.5 and over 4 kg. Body mass index (BMI) at university (median age 19) and in 2001 (median age 62) were positively related to SMF volume, OR per extra kg m À2 1.21 (1.15 -1.28) and 1.17 (1.09 -1.26), respectively, and inversely related to SMF%, OR per extra kg m À2 0.83 (0.79 -0.88) and 0.82 (0.76 -0.88), respectively, Po0.001. Standard Mammogram Form% and absolute SMF volume are related to several, but not all, breast cancer risk factors. In particular, the positive relationship between BMI and SMF volume suggests that volume of dense breast tissue will be a useful marker in breast cancer studies.

Volumetric Breast Density from Full-Field Digital Mammograms and Its Association with Breast Cancer Risk Factors: A Comparison with a Threshold Method

“…Our finding of the dense volume, as measured with the volumetric method, being much larger in women with high BMI would be in agreement with the effect of BMI on breast cancer risk. High BMI was also related to larger dense volume in earlier studies on volumetric methods, based on digitized film screen mammograms (8,14,21). In this way, the volumetric method could provide new insight into the relationship BMI, density, and breast cancer risk.…”

Automated Measurement of Volumetric Mammographic Density: A Tool for Widespread Breast Cancer Risk Assessment

“…In our study, both percent and absolute dense volumes were associated with all known density determinants in the expected direction (Table 3 and Supplementary Table S4). The contrasting effect of BMI on percent and absolute dense volume has been described previously (29,(32)(33)(34) and underscores the notion that the inverse association with percent density is mainly due to the positive correlation between BMI and the amount of nondense fatty tissue. Mammographic density is not only influenced by reproductive and hormonal factors, but is also genetically determined.…”

Differences in breast density assessment using mammography, tomosynthesis and MRI and their implications for practice

“…A reliable method for semi-quantitative PD measurement is possible using the Breast Imaging Reporting and Data System® (BI-RADS) lexicon, developed by the American College of Radiology, Reston, VA, but this method was not originally intended to serve as a method of measuring breast density. Other classifications for density exist (some of which were developed decades ago and are still in use), including Wolfe's parenchymal patterns, Tabar's classification, quantitative assessment using computer-aided techniques for measuring PD and some systems that obtain a volumetric breast density measurement [12,13].…”