by Liz Szabo, USA TODAY
Women are used to making complex choices about mammograms. Should
they start at age 40 or 50? Should they be screened annually or every
other year? Digital or traditional film?
Now, a growing number of
hospitals and radiology centers are asking women to consider yet another
mammography option: Regular or 3-D?
Q. What is a 3-D mammogram?
A.
The technology, called tomosynthesis, provides three-dimensional images
of the breast by using a technology similar to CT scans, or computed
tomography, says Carol Lee, a radiologist at New York's Memorial
Sloan-Kettering Cancer Center and chair of the American College of
Radiology's breast imaging commission. The imaging machine moves around
the breast in an arc, taking multiple X-rays that a computer forms into a
3-D image. The Food and Drug Administration approved tomosynthesis last
year and it's now used in 46 states, according to Hologic, which
manufactures the machines.
Q. Why would someone want a 3-D image of the breast?
A.
Researchers hope that it will reduce the number of false alarms, in
which radiologists call women back for additional mammograms because of
uncertainty about their findings, says Constance Lehman, director of
imaging at the Seattle Cancer Care Alliance, who is leading a clinical
trial on 3-D mammography. About 10% of the 40 million women who get
screening mammograms every year receive a "call back," leading to
anxiety and sometimes additional types of tests, such as ultrasounds,
says Peter Soltani, Hologic's senior vice president of breast health.
Lehman notes, however, that this benefit has not yet been definitively
proven in a rigorously designed study.
There is no data to prove
that tomosynthesis finds more cancer or saves lives, says Fran Visco,
president of the National Breast Cancer Coalition. "3-D is a new
technology that should not be used outside of a clinical trial," Visco
says.
Q. Who could benefit most from 3-D mammograms?
A.
Younger women with dense breasts could potentially benefit the most,
Lee says. That's because radiologists have a harder time picking out
cancers in dense breasts, because both cancers and dense tissue appear
as white on a mammogram. "It's like writing a word on a blackboard and
then covering it in scribbles," Lee says. "By subtracting the scribbles,
you can see the word better." So far, however, studies haven't proven
that 3-D mammograms find significantly more cancers than traditional
mammograms, Lee says. "I personally have yet to be convinced that it's
substantially better," Lee says. "And it doesn't replace a regular
mammogram."
Q. What are the risks and limitations of 3-D mammograms?
A. Because the tests are new, insurance companies may not cover them and may require patients to pay out of pocket.
More
importantly, the procedures give women twice as much radiation as a
standard mammogram, notes surgeon Susan Love, author of Dr. Susan Love's Breast Book. That's because women who get 3-D imaging still undergo traditional 2-D mammography, as well.
Radiation
is a known cause of breast cancer. Researchers in recent years have
become concerned about radiation exposure from medical imaging,
particularly CT scans. A 2009 analysis estimated that CT scans cause
about 29,000 cancers and 14,500 deaths a year. Soltani says the total
radiation dose from 3-D mammography is still relatively low, in spite of
this increase - from 0.5 millisieverts to 1.0 millisieverts. In
comparison, a CT scan of the head has a radiation dose of about 2.0
millisieverts.
But Lehman says a woman's total radiation dose may
not necessarily increase if she undergoes a 3-D mammogram. That's
because the exam may help her avoid the radiation from repeat scans.
Love
says she's skeptical about the technology, which she compares to "a new
toy," noting that the most essential questions about its benefits are
likely to remain unanswered. The most important question about a new
type of screening, Love says, is not simply how well it finds cancer,
but whether it saves lives. She says she doubts the makers of
tomosynthesis are going to perform that sort of large, expensive,
long-term study.
Lee asks, "Is it worth radiating everyone to avoid a few false positives?"
Questions consumers should ask
Consumers
often have to make quick decisions about health care, such whether or
not to undergo a new type of test -- often with little to no time for
research, and sometimes even while wearing little to no clothing.
But
making decisions about health care is far more complicated than picking
a new shampoo, no matter what a glossy brochure may suggest, says
Steven Woloshin, co-director of the Center for Medicine and the Media at
the Dartmouth Institute for Health Policy and Clinical Practice.
Woloshin and other outcomes researchers offer these tips to consider when making medical decisions:
-- There's no free lunch.
Woloshin recommends that patients have a "healthy skepticism," asking
both about the risks, as well as potential benefits, of medical
interventions.
Health care providers may not mention the side
effects, complications or potential downsides to an intervention,
Woloshin says. Questions to ask include: "What is this test supposed to
do? What am I trying to avoid?"
-- Newer isn't always better.
When shopping for a new tech toy, such as an iPhone, new can mean more
faster, cooler, slicker. In health care, "new can mean unproven,"
Woloshin says. "New can be dangerous."
Sometimes, rare side
effects of a new drug don't become apparent until it's been used by tens
of thousands of people. Other times, a new, brand-name drug is simply
more expensive, but no more effective, than older, cheaper therapies,
Woloshin says.
-- More isn't always better. Even painless
tests, such as X-rays and CT scans, have risks, because they expose
patients to radiation, says Fran Visco, president of the National Breast
Cancer Coalition. Other screenings can lead to worry and a cascade of
follow-up tests, which can be far more invasive and painful than the
original test.
Consumers "overestimate what tests can do," Visco
says. "Yet we constantly send out these messages that more is better and
more often is better, although that's rarely the case."
The
American College of Radiology now advises patients to ask questions
before undergoing scans, such as, "How will this exam improve my care?"
and "Are there alternatives that don't involve radiation?"
Remember tomorrow is Buddy Check 10.