Digital X-rays better detectors of breast cancer, new study finds
Published: September 19, 2005
A landmark study co-authored by Canadian researchers has found that digital mammograms are significantly more effective than conventional X-rays in detecting breast cancer in some women.
Trials involving nearly 50,000 women found digital mammograms caught up to 28 per cent more cancers than traditional mammography. The benefits applied to women who were under 50, premenopausal or who had so-called “dense” breasts.
No difference was found for the general population.
“It’s extremely exciting,” said co-author Martin Yaffe, senior scientist in imaging research at Sunnybrook and Women’s College Health Sciences Centre in Toronto.The study — one of the largest breast-cancer-screening trials ever carried out — was funded by the National Cancer Institute in the United States.
When women go for mammograms, the X-ray is traditionally captured on film. But Dr. Yaffe has been a pioneer in digital imaging, which uses electronic pictures instead. Early testing of the technology, beginning in the 1980s, was backed with Canadian funds, making Canada a trailblazer in the field.
As anyone who uses a digital camera knows, the technology allows you to amplify, lighten or manipulate images to enhance the picture. In the case of a mammogram, the image can be stored directly into a computer and shared with other doctors in another location.
The technology also offers promise in making high-quality mammography available even to remote communities in Canada.
Although standard film has improved over the years, it has more trouble penetrating “dense” breasts, which are more prevalent among younger women.
Digital technology is a marked advance. “It’s more of a revolution than an evolution,” Dr. Yaffe said yesterday from Toronto.
While the study found no apparent benefits for women 50 and older, Dr. Yaffe said he expects digital X-rays to be no worse for older women than conventional film.
Digital mammogram equipment remains relatively scarce in Canada. Available since about 2000, only 15 to 20 units are currently in service in the country.
The technology is more expensive than traditional film — up to four times more, according to one estimate. But Dr. Yaffe said he anticipates the cost will come down.
Trials for the study, which began in October, 2001, involved participants at 33 centres in the United States and in Toronto, the sole Canadian location for trials. The women had no signs of breast cancer and received both a digital and film mammogram that was interpreted by two radiologists.
The digital technology picked up 15 per cent more cancers in women with dense breasts, 21 per cent more cancers in women who had not yet gone through menopause, and 28 per cent more cancers in those under the age of 50.
One in nine Canadian women will develop breast cancer at some point during her lifetime. This year, an estimated 21,600 women will be diagnosed with breast cancer and 5,300 will die, making it the most frequently diagnosed cancer in Canadian women.
Radiologist Roberta Jong, director of Breast Imaging at Sunnybrook and Women’s College, was co-principal investigator and a co-author of the study.
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