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Ultrasound Spots Cancers Overlooked by Mammography

Ultrasound Spots Cancers Overlooked by Mammography

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 meeting.

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 Figure 1.)

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."

 
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