Dec 17, 2008
The pros and cons of CAD mammography
Computer programs designed to help radiologists analyse mammograms could identify more cases of breast cancer, but they might also increase the number of false-positive results, which can lead to biopsies in healthy women. That's the conclusion of a recent systematic review from research agency ECRI Institute (Plymouth Meeting, PA).
Computer-aided-detection (CAD) packages are employed within mammography to help radiologists distinguish benign and malignant lesions. The radiologist still reads the mammogram, but the CAD software also evaluates the image and marks suspicious areas for further review. The clinical uptake of CAD, however, has been slowed by concerns over diagnostic accuracy, particularly the number of false positives.
To compile the latest evidence report, ECRI Institute analysts synthesized data from seven previously published studies of CAD mammography in 392,015 healthy women with no lumps or other breast-cancer symptoms. They found that in women with no symptoms, screening with CAD mammography correctly identified 84.2-87.6% of women who had cancer. In addition, 88.1-88.3% of healthy women correctly received negative test results.
The researchers compared the CAD mammography results to biopsy findings and patient follow-up records to determine whether the women had received a diagnosis of breast cancer within the year following the mammogram. The evidence report surmised that CAD mammography helped identify an estimated 50 additional cancer diagnoses for every 100,000 women who underwent the screening test, compared to having the mammogram read only by a radiologist.
The analysis also estimated that following CAD mammography, between 1090 and 1290 women per 100,000 healthy women would be recalled for further testing (in the form of more imaging studies or biopsy) based on abnormal mammogram results. An estimated 80 of those women who had false-positive results would undergo biopsy.
"Using CAD mammography does catch some cases that would have been missed if the mammogram had been read only by a single radiologist," said ECRI Institute research analyst Meredith Noble. Noble notes that physicians should inform women undergoing CAD mammography screening that more false-positives are seen when CAD is used, although some women and their doctors might consider this an acceptable trade-off for identifying additional cancers.
ECRI Institute's new evidence report, Computer-aided Detection (CAD) Mammography for Breast Cancer Screening, is an update of an earlier review. The research agency produces systematic evidence reviews on medical devices, drugs, biotechnologies and procedures as part of its Health Technology Assessment Information Service.