MONDAY, Oct. 17 (HealthDay News) -- Women who undergo mammograms
every two years instead of every year have fewer false-positive
results, but the trade-off is a slightly higher risk of being
diagnosed with late-stage breast cancer, new research finds.
"After 10 years, biennial mammograms reduced the risk of false-positives by about one-third and, over a lifetime, that would accumulate," said Rebecca Hubbard, lead author of a study published in the Oct. 18 issue of Annals of Internal Medicine and funded by the U.S. National
But the increase in breast cancer diagnoses wasn't statistically
significant, she said. And breast cancer stage was only analyzed in
women who actually developed cancer.
On the other hand, among roughly 170,000 women screened between
1994 and 2006 and followed for a decade, more than half who
received annual mammograms were called back at least once because
of a false-positive result, and 7 to 9 percent were recommended to
get a biopsy.
Fewer women -- about 42 percent -- who had biennial screening
were called back because of a false-positive, while 4.8 percent
were referred for a biopsy.
Having a previous mammogram for comparison purposes sliced the
rate of false-positives in half.
For the study, researchers used data from NCI's Breast Cancer
Women undergoing once-yearly mammograms need to be prepared for
possible call backs, and being prepared may reduce the anxiety
around such an event, the authors stated.
This is the latest volley in an ongoing debate about when to
start mammography screening in women.
In 2009, the U.S. Preventative Services Task Force (USPSTF), a
government-sponsored organization, startled the world by
recommending that women start mammograms at age 50 instead of 40
and then only once every two years rather than once a year.
The move released an outcry in the medical community, leading to
this and other studies to try to determine the best timing for
mammograms, the only screening tool shown to reduce deaths from
The new study gives a nod in the direction of the UPSTF
recommendations, but practitioners aren't necessarily ready to let
go of the long-standing once-a-year recommendation.
Hubbard, an assistant investigator with Group Health Research
Institute in Seattle, Wash., said she "definitely wouldn't make a
specific recommendation for individual women. I feel it's really an
individual choice where a woman needs to think about her own risk
tolerance and also their own breast cancer risk."
"This gives women more information as to what the risks and benefits of mammography are," added Dr. Stephanie Bernik, chief of surgical oncology at Lenox Hill Hospital in New York City. "It's a personal choice as to whether or not you absolutely have to screen at 40. As breast surgeons, we're still going to advocate that mammograms start at 40."
A second study in the same journal issue looked at more than
800,000 U.S. women screened from 2000 to 2006 and found that newer
digital mammography and older film mammography were similarly
accurate in finding cancer in women ages 50 through 79.
But in premenopausal women in their 40s, who tend to have denser
breast tissue, digital mammography performed better. Again, though,
the risk of false-positives was higher than with film
"There was a trade-off here as well," said Hubbard, who was also an author of this study. "In general, in women aged 50 to 79 the two modalities performed pretty equivalently, but in younger women the sensitivity of digital mammography was a little bit better so it found more cancers, but there was also a bigger decrease in specificity [resulting in more false-positives]."
The U.S. National Cancer Institute has more on