When mammography and sonography are used together to evaluate palpable breast lesions, they can rule out cancers in most patients, according to a recent study conducted by researchers at Baystate Health in Springfield, MA. However, uncommonly, malignancies cannot be diagnosed using this imaging protocol.
"We were interested in finding out just how effective mammography and sonography were, when used together, in excluding breast cancer in women with palpable findings," said Erica Tyler, MD, lead author of the study. "Our study differs from others because after enrollment, we followed patients for at least 3 years to see if any of the palpable lumps later were diagnosed as malignant," she said.
The study evaluated 414 palpable breast lesions using both mammography and sonography. Imaging of 167 lesions was negative, with normal appearing breast tissue in the area of clinical concern and no mammographic or sonographic findings to explain the palpable finding. Among the 167 women with negative mammography and sonography, 120 reached a diagnostic endpoint with 28 patients undergoing a biopsy that showed no malignancy and 92 patients showing no malignancy after follow-up of at least 36 months. There were 118 true-negative and two false-negative cases said Dr. Tyler. The NPV when using mammography and sonography together was 98%, she said.
The study showed that both false-negative lesions "became increasingly suspicious on clinical exam and later became apparent by imaging," said Dr. Tyler. One false-negative lesion occurred in a patient with heterogeneously dense tissue and was diagnosed 74 months after initial clinical discovery. The second false-negative lesion occurred in extremely dense tissue and was diagnosed 81 months after initial discovery.
"Our findings support those reported in other studies. Uncommonly, palpable malignancies may not be detectable on both mammography and sonography, and this combination of imaging doesn't rule out malignancy," said Dr. Tyler. "Also, based on our findings, long term clinical and imaging follow-up of over five years may be needed to diagnose all palpable cancers, when the initial mammogram and sonogram are unrevealing," she said.
The full results of this study will be presented on Monday, April 14, 2008 during the American Roentgen Ray Society's annual meeting in Washington, DC.
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