A large study shows the latest screening tool can detect more cancers with fewer false positives
Lori Safer is a convert. The 55 year old occupational therapist had been told by many mammogram technicians that her breasts were hard to image. Her fibrocystic tissue meant that every mammography report was somewhat less than reassuring. “They would say, ‘It doesn’t’ look like anything is there, but just come back in a year, and we’ll keep an eye on it,’” the New Jersey resident says.
Worried that the mammograms were not picking up on possible cancers, Safer went to University of Pennsylvania, where the breast imaging center was testing a 3D mammogram, which is the subject of a new study published in JAMA. Building on the 2D technology, the 3D version simply slices the images of the breast and reconstructs them on a computer in 3D form, allowing doctors to get a better view of the entire breast and any potential tumors growing within.
Sure enough, the 3D test picked up a suspicious lump. She got a biopsy, and even that was negative, but because the 3D mammogram had detected a potential tumor, doctors recommended she have a lumpectomy to remove the growth. It turned out to be malignant. But because the cancer was picked up in its earliest stages, before any cancer cells could spread to the lymph nodes, Safer is now cancer-free. “If I had waited a year, like I would have if I had been getting the regular mammogram, it could be a totally different story,” she says.
The latest research on the 3D mammograms, or tomosynthesis, backs her up. Led by Dr. Sara Friedewald, chief of breast imaging at Advocate Lutheran General Hospital in Illinois, researchers report that 3D mammograms can pick up more breast cancers and lead to fewer callbacks for repeat testing than 2D mammography. It’s the data that many breast cancer physicians have been waiting for.
Since the Food and Drug Administration approved the first 3D mammogram machine in 2011, doctors have been documenting whether the technology can outperform existing mammography by improving detection of breast cancer while cutting back on false positives. In the JAMA study, the researchers collected data from more than 454,000 mammograms done at 13 sites; nearly a quarter included both the traditional 2D mammogram as well as an additional 3D image. Compared to the 2D mammograms alone, the tomosynthesis improved detection of invasive cancers by 41%, while not increasing rates of picking up DCIS cancers, which don’t spread from the milk ducts and have higher survival rates. That’s important because other technologies, including ultrasound and MRI, led to higher rates of detecting all types of growths, but it’s more important to identify early-stage invasive cancers because treating them can lead to higher remission rates and longer survival.
“In my long career, this is the biggest improvement in screening I have seen,” says Dr. Emily Conant, professor or radiology and chief of breast imaging at the University of Pennsylvania Perelman School of Medicine and one of the study’s co-authors. “This is much bigger than the improvement in going from analogue or film to digital; I don’t think there’s a doubt about that.”
The study is the largest to show that 3D mammograms can increase the detection of invasive cancers while lowering the rate of recall testing. “That’s a critical point of 3D,” says Friedewald. “Other screening modalities [such as ultrasound and MRI] have shown that they can pick up additional cancers but none have simultaneously reduced the number of recalls.” Fewer recalls can lead to fewer risks, and costs, for women. Safer, for example, says that she has been called back after a mammogram at least six or seven times for additional testing, which contributed to more time and costs for her, not to mention psychological stress about whether she had cancer.
With these findings, the focus will now shift to figuring out how often women need to be screened using the 3D technology, and how to phase in the machines, which cost $500,000. Not all insurers cover the cost of the 3D screening, which is slightly more expensive than traditional mammography. That could also mean that women requesting it will pay more out-of-pocket as well.
The 3D machines used in the study required women to get double the dose of radiation of a regular mammogram, which was still below the safe levels established. But newer versions of the technology will bring that exposure down to levels similar to those of current mammography machines.
Should every hospital switch to imaging? “I think it’s premature to replace 2D mammography, since we are still trying to understand the utility and limitations of the technology,” says Dr. Therese Bevers, medical director of the cancer prevention center at the University of Texas MD Anderson Cancer Center. “But a test that weighs more favorably toward benefits—and fewer callbacks—is a win-win.”
The researchers hope that that results will convince more insurers to cover 3D imaging on the premise that despite its higher upfront cost, the test’s sensitivity in detecting invasive cancers would lead to cost savings by avoiding costly follow ups and additional testing.
For Safer, there’s no question about what type of mammogram she will be getting from now on. “I called all my friends and relatives, and told them you can’t just go for a regular mammogram,” she says. “I told them they have to go online to find places that have 3D.”
If these results hold up, then those facilities won’t be so hard to find in the near future.