Introduction: Dense breasts are common in Asian women and they limit the sensitivity of mammography. This study evaluates the performance of supplementary breast ultrasound screening in Asian women with dense mammograms.Materials and Methods: The study was approved by the hospital’s Institutional Review Board. A prospective clinical trial was performed between September 2002 and November 2004. Asymptomatic Asian women with negative and dense mammograms were offered supplementary ultrasound screening for breast cancer. Ultrasound assessment was categorised as U1 to U4. U1 and U2 cases were recommended routine interval screening mammography. U3 cases were recommended follow-up ultrasound in 6 months and routine interval screening mammography and U4 cases were recommended biopsy. Results: One hundred and forty-one women with mean age of 45.1 years were enrolled into the study. Mean scan time was 13.0 minutes (± 5.6 minutes) for bilateral vs 11.0 minutes (± 1.4 minutes) for unilateral scans. There were 10 patients and 14 patients in the in the U3 and U4 categories, respectively. Two U4 category patients were diagnosed with malignancy—a-6 mm ductal carcinoma-in-situ and a 13- mm invasive ductal carcinoma. The breast cancer detection rate was 1.4%. Sensitivity and specificity were 100% (2/2) and 88.5% (92/104) respectively. The positive predictive value was 14.3% (2/14) and the negative predictive value was 100% (92/92). Conclusion: This pilot study reveals the usefulness of supplementary ultrasound screening in detecting early stage mammographically and clinically occult breast cancers in Asian women with dense breasts. A larger long-term study is, however, needed to assess its feasibility and impact on breast cancer prognosis.
Mammogram has been the gold standard for breast cancer screening and Magnetic Resonance Imaging (MRI) has been advocated for screening of high- risk individuals. However, there is currently no recommendation for supplementary ultrasound scan in breast cancer screening. Moreover, it is known that dense breasts, which are common in Asian women, reduce the sensitivity of detecting breast cancers on mammogram by as much as 50% compared to fatty breasts. Furthermore, increased breast density is associated with a higher risk for breast cancer and development of interval cancers between screening mammograms.
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