The addition of an ultrasound examination to mammography for women at high risk of breast cancer resulted in a higher rate of cancer detection, but also increased the number of false-positive results, according to a new study.
Supplemental ultrasound screening has the potential of depicting small, node-negative breast cancers not seen on mammography, according to background information in the article.
Against such a background, doctors conducted a study to compare the diagnostic effectiveness of screening breast mammography plus ultrasound versus mammography alone in women at increased risk of breast cancer. The study included 2,809 women with dense breast tissue who were randomised to undergo mammographic and ultrasonographic examinations.
Some 40 participants – with 41 breast lesions – were diagnosed with cancer: eight suspicious on both ultrasound and mammography; 12 on ultrasound alone; 12 on mammography alone; and eight participants – involving nine breast lesions – on neither.
The diagnostic yield for mammography was 7.6 cancers per 1,000 women screened; 31 cancers were diagnosed in 2,637 participants by the combination of mammography plus ultrasound, producing a yield of 11.8 per 1,000 women, and an increased yield due to ultrasound of 4.2 per 1,000 over mammography alone.
The diagnostic accuracy of mammography was 0.78; for ultrasound, 0.80; and for combined mammography plus ultrasound, 0.91. The positive predictive value of biopsy recommendation after full diagnostic workup was 19 of 84 for mammography (22.6 per cent), 21 of 235 for ultrasound (8.9 per cent), and 31 of 276 for combined mammography plus ultrasound (11.2 per cent).
The false-positive rate for mammography was 4.4 per cent; for ultrasound, 8.1 per cent; and for combined mammography plus ultrasound, 10.4 per cent.
In an accompanying editorial, Dr Christiane K. Kuhl, of the University of Bonn, Germany, commented: “Increasing evidence suggests that for many women, mammography does not provide the best possible accuracy. Early diagnosis is important and has been the single major reason for improved breast cancer survival rates. Notwithstanding this success, a success mainly credited to mammographic screening, there is good reason to move on. As long as breast cancer remains the most common cause of cancer death in women, the search for techniques that can help cover the limitations of mammograpy screening must continue.”
Dr Kuhl added that “mammographic screening has been in use for more than 40 years. It may now be time to carefully reconsider. Individualised screening schemes tailored to the individual risk and to the personal preferences of a woman may be the way to consider how to screen for breast cancer. Whether in the long run, ultrasound or breast MRI will be more appropriate for this purpose remains to be seen.”
JAMA
2008;299:2086-2087,2151-2163
About Terence Cosgrave
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