Current recommendations for women who have a BRCA1 or BRCA2 mutation are to undergo breast surveillance
from age 25 years onward with mammography annually and clinical breast examination
(CBE) every 6 months; however, many tumors are detected at a relatively advanced
stage. Magnetic resonance imaging (MRI) and ultrasound may improve the ability
to detect breast cancer at an early stage.
To compare the sensitivity and specificity of 4 methods of breast cancer
surveillance (mammography, ultrasound, MRI, and CBE) in women with hereditary
susceptibility to breast cancer due to a BRCA1 or BRCA2 mutation.
Design, Setting, and Participants
A surveillance study of 236 Canadian women aged 25 to 65 years with BRCA1 or BRCA2 mutations who underwent
1 to 3 annual screening examinations, consisting of MRI, mammography, and
ultrasound at a single tertiary care teaching hospital between November 3,
1997, and March 31, 2003. On the day of imaging and at 6-month intervals,
CBE was performed.
Main Outcome Measures
Sensitivity and specificity of each of the 4 surveillance modalities,
and sensitivity of all 4 screening modalities vs mammography and CBE.
Each imaging modality was read independently by a radiologist and scored
on a 5-point Breast Imaging Reporting and Data System scale. All lesions with
a score of 4 or 5 (suspicious or highly suspicious for malignancy) were biopsied.
There were 22 cancers detected (16 invasive and 6 ductal carcinoma in situ).
Of these, 17 (77%) were detected by MRI vs 8 (36%) by mammography, 7 (33%)
by ultrasound, and 2 (9.1%) by CBE. The sensitivity and specificity (based
on biopsy rates) were 77% and 95.4% for MRI, 36% and 99.8% for mammography,
33% and 96% for ultrasound, and 9.1% and 99.3% for CBE, respectively. There
was 1 interval cancer. All 4 screening modalities combined had a sensitivity
of 95% vs 45% for mammography and CBE combined.
In BRCA1 and BRCA2 mutation
carriers, MRI is more sensitive for detecting breast cancers than mammography,
ultrasound, or CBE alone. Whether surveillance regimens that include MRI will
reduce mortality from breast cancer in high-risk women requires further investigation.