CHICAGO--Although mammography is the best screening tool for breast
cancer, it misses carcinoma in 15% or more of women with dense breasts.
Supplemental, bilateral, high-resolution ultrasound can find these malignancies,
Thomas M. Kolb, MD, a New York City radiologist who specializes in breast
cancer detection, reported at the Radiological Society of North America
In a study by Dr. Kolb and his colleagues Drs. Jacob Lichy and Jeffrey
Newhouse, ultrasound examination of women with dense breasts who had normal
mammograms and no abnormalities on physical examination increased the detection
of breast cancer by nearly 16% and raised by 30% the number of tumors detected
by imaging only.
Ten of 250 Masses Malignant
Follow-up ultrasound studies detected 250 solid masses that had not
been observed on mammography or palpated during physical examination of
2,600 women with dense breast tissue. Ten of these masses proved to be
malignant at biopsy.
Ultrasound also spotted breast tumors that were small in size and at
an early stage. The average size of the malignancies found with ultrasound
was 11.3 mm, which was nearly identical to the 11.2 mm average size for
cancers observed on mammography and about half the size of tumors that
were found by palpation.
Eighty-seven percent of the malignancies seen on ultrasound were stage
0 or stage 1, compared with 92% of the tumors detected with mammography.
But only 40% of palpable tumors were low stage.
Ultrasound is especially helpful in the evaluation of women with dense
breasts. "The sensitivity of the mammogram is reduced in these women
because breast cancer that appears white on the mammo-gram can be hidden
in dense glandular tissue, which is also white," Dr. Kolb said. (See
Fortuitously, he added, the appearance of a cancer on ultrasound is
just the opposite; it is dark, which stands out in a white background,
"allowing us to detect cancers in dense breasts that would have been
otherwise missed." (See Figure 2.)
In his study, assuming $150 for ultrasound, $300 for an ultrasound-guided
biopsy, and $1,500 for surgical biopsy, each of the 10 cancers detected
with ultrasound by Dr. Kolb cost $36,000 over and above the cost of screening
mammog-raphy and physical examination. "It is important to understand
that an ultrasound examination does not replace a mammogram but rather
may add additional information," he said.
Dr. Kolb hesitated to recommend routine ultrasound screening: "Before
widespread use of the technique is instituted, analysis of mortality reduction
and a more thorough cost analysis are necessary."