New 3-D mammograms have benefits, risks

• Tomosynthesis provides 3-D images of breast
• Researchers hope method will reduce false alarms
• Insurance companies may not cover such tests

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?

USA TODAY's Liz Szabo asked screening experts to talk about the risks, limitations and potential benefits of this new method of early cancer detection.

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?"