Visually assessed breast density, breast cancer risk and the importance of the craniocaudal view.
BACKGROUND
Mammographic density is known to be a strong risk factor for breast cancer. A particularly strong association with risk has been observed when density is measured using interactive threshold software. This, however, is a labour-intensive process for large-scale studies.


METHODS
Our aim was to determine the performance of visually assessed percent breast density as an indicator of breast cancer risk. We compared the effect on risk of density as measured with the mediolateral oblique view only versus that estimated as the average density from the mediolateral oblique view and the craniocaudal view. Density was assessed using a visual analogue scale in 10,048 screening mammograms, including 311 breast cancer cases diagnosed at that screening episode or within the following 6 years.


RESULTS
Where only the mediolateral oblique view was available, there was a modest effect of breast density on risk with an odds ratio for the 76% to 100% density relative to 0% to 25% of 1.51 (95% confidence interval 0.71 to 3.18). When two views were available, there was a considerably stronger association, with the corresponding odds ratio being 6.77 (95% confidence interval 2.75 to 16.67).


CONCLUSIONS
This indicates that a substantial amount of information on risk from percentage breast density is contained in the second view. It also suggests that visually assessed breast density has predictive potential for breast cancer risk comparable to that of density measured using the interactive threshold software when two views are available. This observation needs to be confirmed by studies applying the different measurement methods to the same individuals.
Duffy
Stephen W
SW
Department of Epidemiology, Mathematics and Statistics, Wolfson Institute of Preventive Medicine, Charterhouse Square, London EC1M 6BQ, UK. stephen.duffy@cancer.org.uk
Nagtegaal
Iris D
ID
Astley
Susan M
SM
Gillan
Maureen G C
MG
McGee
Magnus A
MA
Boggis
Caroline R M
CR
Wilson
Mary
M
Beetles
Ursula M
UM
Griffiths
Miriam A
MA
Jain
Anil K
AK
Johnson
Jill
J
Roberts
Rita
R
Deans
Heather
H
Duncan
Karen A
KA
Iyengar
Geeta
G
Griffiths
Pam M
PM
Warwick
Jane
J
Cuzick
Jack
J
Gilbert
Fiona J
FJ
D001940:Breast / Q000473:pathology*; D001943:Breast Neoplasms / Q000175:diagnosis* / Q000473:pathology*; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods; D008327:Mammography / Q000379:methods*; D008403:Mass Screening / Q000379:methods; D016017:Odds Ratio; D015203:Reproducibility of Results; D012306:Risk; D018570:Risk Assessment / Q000379:methods; D012307:Risk Factors; D012984:Software