Is mammography adequate for screening women with inherited BRCA mutations and low breast density?
BACKGROUND
Several observational studies have shown that magnetic resonance imaging (MRI) is significantly more sensitive than mammography for screening women over age 25 at high risk for hereditary breast cancer; however, MRI is more costly and less specific than mammography. We sought to determine the extent to which the low sensitivity of mammography is due to greater breast density.


METHODS
Breast density was evaluated for all patients on a high-risk screening study who were diagnosed with breast cancer between November 1997 and July 2006. Density was measured in two ways: qualitatively using the four categories characterized by the Breast Imaging Reporting and Data System and quantitatively using a computer-aided technique and classified as (a) <or=10%, (b) 11% to 25%, (c) 26% to 50%, and (d) >50% density. Comparison of sensitivity of mammography (and MRI) for each individual density category and after combining the highest two and lowest two density categories was done using Fisher's exact test.


RESULTS
A total of 46 breast cancers [15 ductal carcinoma in situ (DCIS) and 31 invasive] were diagnosed in 45 women (42 with BRCA mutations). Mean age was 48.3 (range, 32-68) years. Overall, sensitivity of mammography versus MRI was 20% versus 87% for DCIS and 26% versus 90% for invasive cancer. There was a trend towards greater mammographic sensitivity for invasive cancer in women with fattier breasts compared with those with greater breast density (37-43% versus 8-12%; P = 0.1), but this trend was not seen for DCIS.


CONCLUSIONS
It is necessary to add MRI to mammography for screening women with BRCA mutations even if their breast density is low.
Bigenwald
Rachel Z
RZ
Division of Medical Oncology, Sunnybrook Health Sciences Centre, Toronto, Ontario, Canada.
Warner
Ellen
E
Gunasekara
Anoma
A
Hill
Kimberley A
KA
Causer
Petrina A
PA
Messner
Sandra J
SJ
Eisen
Andrea
A
Plewes
Donald B
DB
Narod
Steven A
SA
Zhang
Liying
L
Yaffe
Martin J
MJ
D000328:Adult; D000368:Aged; D001940:Breast / Q000033:anatomy & histology* / Q000473:pathology; D001943:Breast Neoplasms / Q000000981:diagnostic imaging* / Q000235:genetics*; D018270:Carcinoma, Ductal, Breast / Q000000981:diagnostic imaging* / Q000235:genetics*; D019398:Genes, BRCA1; D024522:Genes, BRCA2; D020022:Genetic Predisposition to Disease; D006801:Humans; D008327:Mammography; D008403:Mass Screening; D008875:Middle Aged