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The screening and diagnostic
tools for detecting and diagnosing breast cancer have become more and more accurate since
the early 1970s when modern mammography started to become widely available. Massive
research and development and clinical refinement have made the entire process quite
precise. The American College of Radiology (ACR) has developed the Breast
Imaging Reporting and Data System™ (BI-RADS™) to categorize mammography findings.
The theoretical clinical decision tree
for detecting and diagnosing breast cancer has been refined to a very high level. However,
the actual numbers and statistics shown below can vary from region to region depending on
population density and patient demographics.
Screening
mammography on an annual basis is now recommended for all women over the age 40. Of
all of the screening mammograms performed annually approximately:
- 90% of all screening mammograms show no
evidence of cancer (BI-RADS™ category 1)
- 10% of all screening mammograms show
abnormalities which require further diagnostic testing (BI-RADS™ category 0)
Of those referred for additional
diagnostic testing and further views (which may include diagnostic
mammography, special mammography views, breast ultrasound or other adjunctive imaging such as MR, Sestamibi or T-scan) approximately:
- 30% are determined to be normal
(BI-RADS™ category 1) or contain benign findings (BI-RADS™ category 2) which do
not require further evaluation (beyond recommended annual screening mammography)
- 35% are determined to be probably benign
(BI-RADS™ category 3) and require closer monitoring and follow up within the next 6
months
- 20% (approximately 2% of all screening
mammograms) are shown to be abnormal and require biopsy (BI-RADS™ category 4 or
category 5)
- 15% are shown to have cysts (usually
using ultrasound) and require no intervention or biopsy (BI-RADS™ category 2)
Of those referred for biopsy
approximately:
- 80% of the abnormalities are shown to be
benign
- 20% of the abnormalities are shown to be
cancerous
The "breast
cancer diagnosis triangle" describes the relationship of the
diagnostic decision tree (described above) and the breast cancer found.
Updated: May 4, 2008
Mammogram
"categories" and ACR/BI-RADS™ Mammography Reporting System
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