Digital mammography was much better than traditional film mammography at spotting breast cancers in younger women or those with dense breasts, U.S. researchers said on Tuesday.
The results confirm earlier findings and better define who will benefit from the newer, more costly digital exams.
Early findings from this same study of 49,528 women published in 2005 suggested that younger women and women with dense breasts would benefit, but also found the digital test was no better than traditional film-based mammography for the overall population of women.
"This paper confirms that if you are under 50, pre- or perimenopausal, and have dense breasts, you should definitely be screened with digital rather than film," Dr. Etta Pisano of the University of North Carolina School of Medicine in Chapel Hill said in a statement.
Unlike traditional mammograms, digital mammograms can be stored on a computer and the images can be enhanced and sent electronically. Digital mammograms also use less radiation than film mammograms. But the digital systems cost about 1.5 to 4 times more than film systems.
In the study, published in the journal Radiology, the researchers sought to determine which women would benefit most from the more costly tests.
They looked at the results of The Digital Mammographic Imaging Screening Trial or DMIST — begun in 2001 — which compared the two types of mammograms.
Women in the study were considered premenopausal or perimenopausal if they had a menstrual period with 12 months of their mammograms. Women typically enter menopause between the ages of 45 and 55, with the average age being 51.
Pisano and colleagues looked at the results of several different subgroups of women, including those of different age groups and those with dense or fatty breasts.
Dense breast tissue can make a mammogram harder to read than fatty breast tissue. And other studies have shown women with dense breast tissue — who are usually younger — have a higher risk of cancer.
The new analysis confirmed that the digital system was better for pre- and perimenopausal women under 50 years old with dense breasts.
For women over 65 with fatty breasts, film appeared to work better. For other groups, there was no significant difference between the two.
Dr. Stamatia Destounis, a radiologist at the Elizabeth Wende Breast Clinic in Rochester, New York, offers both types of mammograms.
"If you are a young lady and you fulfill the criteria, we steer you toward digital and keep you there," Destounis said in a telephone interview. "For patients with fatty breasts and the elderly, it's just fine to use film."
"I think this study confirms that the initial results were accurate. This wasn't a fluke."
According to the World Health Organization, more than 1.2 million people will be diagnosed with breast cancer this year. Breast cancer will kill more than 40,000 Americans this year.
The American Cancer Society recommends women age 40 and older get a mammogram every year.
