Breast density and outcome of mammography screening: a cohort study.
The purpose of this study was to investigate the effect of breast density on breast cancer (BC) mortality in a mammography screening programme. The cohort included 48 052 women participating in mammography screening in Copenhagen, Denmark, where biennial screening is offered to women aged 50-69 years. We collected information for the years 1991-2001 on screening outcome, incident BCs (screen-, interval-, and later detected), and BC deaths. Breast density was dichotomised into fatty (F) and mixed/dense (M/D) breasts. Screening sensitivity was measured as the odds ratio of interval versus screen-detected cancer for dense versus F breasts. Poisson regression was used to estimate the ratios for BC incidence, case fatality, and mortality between women with M/D and F breasts. For women with M/D breasts, the odds ratio of an interval cancer was 1.62 (95% confidence interval, CI, 1.14-2.30), and the age-adjusted rate ratios were 2.45 (95% CI 2.14-2.81) for BC incidence, 0.60 (95% CI 0.43-0.84) for case fatality, and 1.78 (95% CI 1.17-2.72) for BC mortality. The study shows that BC in women with M/D breasts is more frequent, but on average less severe, than in women with F breasts.
Olsen
A H
AH
Department of Epidemiology, Institute of Public Health, University of Copenhagen, Copenhagen, Denmark. a.h.olsen@pubhealth.ku.dk
Bihrmann
K
K
Jensen
M-B
MB
Vejborg
I
I
Lynge
E
E
D000368:Aged; D001940:Breast / Q000473:pathology*; D001943:Breast Neoplasms / Q000737:chemistry / Q000453:epidemiology / Q000401:mortality*; D015331:Cohort Studies; D005260:Female; D006801:Humans; D015994:Incidence; D008327:Mammography; D008403:Mass Screening; D008875:Middle Aged; D016012:Poisson Distribution; D011960:Receptors, Estrogen / Q000032:analysis
D011960:Receptors, Estrogen