A recent study shows that by comparison, reading mammograms
by two different radiologists, versus using just one radiologist aided by a
computer, yields a similar rate of cancer detection.
The randomized study, which included 31,000 women, found
that of 227 cancers, 198 – that’s 87.2% – were detected by a radiologist using
a computer, very close to the 199 – 87.7% – detected by a pair of radiologists
working in tandem.
This is good news for Britain, as in that country the
standard practice for cancer screening is to use two independent radiologists;
however in some more remote locations, sufficient staff is not always
available, and some women aren’t invited for screenings as often as they should
be. The findings of the study encourage more hospitals and medical practices to
use Computer-Aided Detection (CAD), in interpreting mammograms, as this will
make cancer screening more available to women who previously had limited
access.
"Women should be reassured that the final decision on
recall is made by the human reader using their knowledge and experience to
decide if any areas of the mammogram marked by CAD merit further
investigations," said Dr. Fiona Gilbert, professor of radiology with the University of Aberdeen
in Scotland.
Using CAD, according to Dr. Gilbert, could improve the
detection rate by as much as 10% in centers which have a shortage of readers
and currently use only single reading. It has also been speculated that the
detection rate of the computer method would increase even further if digital
mammography was used in conjunction with this system. The comparative study
which is the object of this article was conducted by using scanned copies of
mammography films. This is essentially checking a copy, which may result in
some information being lost to the computer. Thankfully most modern cancer
screening centers do use digital mammography even if they don’t use CAD.
The find is also of great interest to screening centers
across the United States,
where the policy is currently to use a single reader, unaided. As explained by
the director of breast imaging for Southfield, Michigan’s Providence
Hospital, Dr. Thomas Hall, "Most
mammograms are single-read in America,
though most places now, when they get digital mammography, also get CAD."
Dr. Carol H. Lee, radiologist for the Memorial
Sloan-Kettering Cancer
Center in New
York and the head of the American College
of Radiology's Breast Imaging Commission remarked that "In the United
States, it's just not practical in most practices to do double readings by
physicians. These results are reassuring to me that single reading with CAD can
achieve that same sensitivity."
According to U.S.
government recommendation, women over the age of 40 should get mammograms every
one or two years, however there aren’t enough radiologists to do that and
insurance companies don’t usually pay for a second reading. Medicare however,
pays for computer-aided detection.
