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Keywords:
Epidemiology, Screening, Mammography, Breast
Authors:
S. L. Heller, S. M. Hudson, L. Wilkinson; London/UK
DOI:
10.1594/ecr2015/C-1398
Results
Screening Population
32,685 screening records were evaluated (age range 41-90).
Figure 2 shows the distribution of the ages in the study according to prevalent versus incident screen.
The distribution reflects the parameters of the Southwest London United Kingdom screening program; during the time period of the study,
women ages 49-70 were invited for screening.
(Women younger than 49 are most likely to be high risk and therefore enrolled in special screening protocols; women older than 70 are self-referred for screening.)
Age and Density
Breast density was plotted versus age for breast volume,
fibroglandular tissue volume,
and Volapara breast density% for the population (Figs.3-8).
The distribution of the %VBD including Volpara Grades for the standard screen population is similar across age range (Figs.3-4).
Half of women have a breast volume between 500 and 1000 cm3,
regardless of age (Fig.4).
FGV is also distributed similarly regardless of age,
but there is a slight downward trend (Figs.5-6).
Volpara percentage density and Volpara density grades were also plotted versus age (Figs.
7-8).
A negative trend for age versus percentile density is noted in women younger than 56.
The distribution of the density measurements changes above age 55,
to become even more skewed; in other words,
older women in our study have generally less dense breasts,
but there is more variability towards the upper range of measurements.
Notably dense breasts (Volpara Grade 4) are still noted in some women in the older age groups (Figs.7-8). There are many fewer women > 70 in the screening cohort as this group is only screened on request,
but fewer of these women have very fatty breasts than the standard screeing cohort (Fig.7).
Density and Ethnicity
The breakdown of self-reported ethnic groups based on preset Office of National Statistics 2011 Categories is as follows:
- Black includes Black African,
Black British,
Black Caribbean
- White includes White British,
White Irish,
and Any other White background
- Asian includes Asian British,
Bangladeshi,
Indian,
Pakistani.
- Chinese is identified as a separate ethnic category.
Table 2 depicts the mean range of breast volume,
FGV,
and Volpara breast density% for each group.
The majority of women (64%; 20,898/32,685) recorded their ethnicity as White.
Women of Chinese ethnicity had highest Volpara %density (11.0),
(p<.001) and significantly lowest breast volume (360-380 cm3) (Table 2 and Fig.9).
Black women had significantly higher breast volume as compared to other groups,
but also higher FGV. Thus this group's breast density does not differ substantially from the rest of the cohort.
There does not appear to be any difference between ethnic groups density trends when viewed by age (Fig.10).
Density and Deprivation Index
Breast density was categorized according to deprivation data divided into quintiles (1-5,
most deprived to least deprived).
In our population,
women in the most deprived quintiles tend to have larger and therefore less dense breasts (Fig.11).
Age had no effect on density when evaluated for each deprivation quintile.