What is the accuracy of mammography to detect breast cancer?

Updated: Oct 17, 2016
  • Author: Nagwa Dongola, MD, FRCR; Chief Editor: Peter Eby, MD  more...
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False-positive results may arise when benign microcalcifications are regarded as malignant. Tissue summation shadows may appear as local parenchymal distortion; this may be erroneously called suspicious tissue. A benign circumscribed lesion may show signs suggestive of malignancy, along with other findings, such as an irregular border and no halo sign.

According to data from the Breast Cancer Detection Demonstration Project, the false-negative rate of mammography is approximately 8-10%. Approximately 1-3% of women with a clinically suspicious abnormality, a negative mammogram, and a negative sonogram may still have breast cancer.

Possible causes for missed breast cancers include dense parenchyma obscuring a lesion, poor positioning or technique, perception error, incorrect interpretation of a suspect finding, subtle features of malignancy, and slow growth of a lesion.

Birdwell et al performed a multicenter study and found that, on prior mammograms with missed cancers, 30% of the lesions were calcifications, with 17 of 49 clustered or pleomorphic. Approximately 70% were mass lesions, with 40% spiculated or irregular. For calcifications and masses, the most frequently suggested reasons for possible miss were dense breasts (34%) and distracting lesions (44%). [8]

Some cancers (eg, mucinous carcinomas) may have well-defined borders and mammographic features suggestive of benignancy.

The false-positive rate of recommendation for biopsy is 4.3-6.7/1000, and 64-84/1000 need additional imaging after screening. Using an annual screening regimen, 61% of patients will receive a recall from screening after 10 years, and 7% will have a recommendation for biopsy. [9]

DCIS has increased from 2.4/100,000 to 27.7/100,000 since screening. Fifty percent of all recurrences after DCIS are invasive. Long-term follow-up of low-grade DCIS treated only by biopsy without definitive excision or radiation therapy is associated, at 30 years, with a 30-60% incidence of invasive cancer. [10]

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