Diagnostic Mammography Tool Might Not Increase Test Accuracy

An emerging study reveals that computer-aided detection (CAD), a mammography tool that helps in digital image analysis, may not be as efficacious as originally believed.

CAD is meant to increase early detection of very early and non-invasive breast cancers; however, women without cancer must go through ultrasounds and biopsies in follow-up care, said Reuters Health. CAD is used on digital mammograms as well as digitized iterations of traditional x-ray mammogram films, said the American College of Radiology and the Radiological Society of North America, explained Reuters Health.

The study found CAD use has increased, now being used in more than 60 percent of screening mammograms used in women covered under Medicare in 2006, Reuters Health said. But, said Dr. Joshua Fenton, the study’s lead author, it is unclear if the tool does or does not help.

Dr. Fenton, from the University of California, Davis, said that it is unknown if there are any benefits in treating very early cancers—ductal carcinoma in situ (DCIS)—aggressively, especially in women who are in their late 60s and older, Reuters Health said. Women diagnosed with DCIS are typically urged to undergo surgery and sometimes, even, to undergo radiation and anti-cancer medications. “At this time we just don’t know whether detecting these cancers reduces a woman’s chance of dying of breast cancer,” Fenton told Reuters Health.

UC Davis explained that the tool is broadly used and costly and, while CAD does help in the detection of DCIS, CAD also makes more errors than traditional mammography, citing the research.

DCIS is a non-invasive breast lesion, known as a “stage 0” cancer as it does not typically impact either mortality or surrounding breast tissue, UC Davis explained. “DCIS progresses slowly, if at all,” said Fenton. “Some of these early noninvasive lesions may never have come to clinical attention in women’s lifetimes if CAD were not applied to their mammograms,” he added, sad UC Davis.

Meanwhile, over-testing women who do not have cancer provides does not seem to provide benefit and may present harm to these women. “CAD has been broadly adopted, largely due to Medicare coverage that began in 2001, and after 12 years and over a billion dollars spent on CAD it’s still unclear if any benefits of CAD outweigh its risks,” Fenton told Reuters Health.

The research found that CAD mammography was associated with more diagnostic testing, such as breast biopsy, in women who did not have breast cancer. “This means that CAD increases the chances of being unnecessarily called back for further imaging or tests because of a false alarm, which is already a major problem without CAD,” said study co-author Joann Elmore, a professor of internal medicine and epidemiology at the University of Washington and a specialist in breast cancer screening. “No woman likes receiving a notice saying that there was an abnormality on her mammogram that might or might not be cancer and more testing is necessary. This can understandably be a very stressful experience for women,” Elmore added, said UC Davis.

Women without breast cancer who were screened with the CAD tool were 7 percent likelier to have to undergo a breast ultrasound and 10 percent likelier to undergo a biopsy following a false positive diagnosis. “The consequence is, you need more recall, more additional imaging tests, more biopsies, and this is a problem that hurts individually the patient and society, as medical care costs will be high,” Bin Zheng, a University of Pittsburgh radiology researcher not involved in the study, told Reuters Health. “Even in studies that have included younger women, (CAD) has been associated with a higher rate of false positives and more biopsies,” Fenton said.

CAD-assisted mammograms increased from 3.6 percent when the study began to 60.5 at the study’s final year, said Fenton’s team reporting in the Annals of Internal Medicine. Use of CAD increased DCIS cancer identification by 17 percent, said Reuters Health. The number of invasive cancers detected did not change with the CAD tool. CAD was also deemed useful in detecting breast calcifications, said Zheng, who pointed out that the tool over-diagnoses larger masses, wrote Reuters Health.

The team analyzed data from a national study involving 163,800 women who were between 67 and 89 years of age and who underwent two or three mammograms from 2001 to 2008.

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