Ask any radiologist and they will tell you that the mammogram is the gold standard for detecting breast cancer. That’s largely because of the volume of randomized control trial data in support of mammography’s effectiveness, including over the long-term, says Dr. Bonnie Joe, chief of breast imaging at the Department of Radiology and Biomedical Imaging at the University of California, San Francisco. “The mammogram is the only one proven, in these trials, to save lives from cancer.”
It’s also because mammography can detect calcifications in the breast, a potential sign of cancer. “To compete with mammography is almost impossible, because it works so well,” says Dr. Avice O’Connell, professor of imaging sciences and director of women’s imaging at the University of Rochester.
That god-awful compression is key. “When you compress the breast, you reduce its motion,” explains Dr. Jean Kunjummen, director of the Breast Imaging Center at Emory University Hospital Midtown. “Even breathing can cause blurry images, and then you don’t find the small [early stage] cancers.” The smaller the cancer, the better the chances of treating it, says Dr. Kunjummen. “Size matters.”
Compression also reduces the amount of radiation that’s needed during the screening because it’s easier to “see” through a flattened breast.
Mammography may be queen, but there are other options — though all carry significant drawbacks. Ultrasound, for example, has a high false positive rate. Molecular breast imaging (MBI), in which a radioactive tracer is injected intravenously, then viewed with a gamma camera, exposes the entire body to radiation, not just the breasts. The dose is too high (30–40 times higher than mammography) to do annually.
MRI works well, but the cost is exorbitant, and insurance companies balk at covering it. And don’t even think about thermography, a test popular with naturopathic doctors that consists of using infrared imaging to pick up on hotter areas with increased blood flow, which its practitioners believe could indicate cancer. “It’s quackery,” says Dr. Joe. “I have never, in my experience, seen a thermogram that found a cancer. But we have seen thermograms that miss cancer.”
So, we’re stuck with mammography. At least it’s getting better-ish. The next generation, tomography or 3D mammography, creates an image that can be examined in one-millimeter, cross-section layers, similar to the pages of a book. It still uses compression, but it allows doctors to see more with increased clarity, with about the same dose of radiation as a 2D mammogram.
We can send men to the moon, but we can’t create a better way to find breast cancer?
Dr. O’Connell believes tomography will replace 2D digital mammography, once more insurance companies get on board. Insurers are required to fully cover one annual 2D mammogram for women over 40. Because tomography is newer and more expensive, not all insurance companies cover it without some cost sharing. My own insurance company just started fully covering 3D screenings this year.
Manufacturers are trying to make mammography more comfortable as well. Some new units have rounded instead of sharp plate edges. A few have foam padding for the compression panels — and honestly, why aren’t those standard already?
Another new development is self-compression — as in, you help control the final amount of compression yourself using a remote control device. “That way the technician doesn’t accidentally overdo it, because we never want to compress to pain,” Dr. Joe says. That’s also not available everywhere.
What if breast screening for cancer had been designed by women from the start? Starting in 1913, German surgeon Albert Salomon began using X-rays to detect early signs of cancer, but it was Uruguayan radiologist Raul Leborgne who introduced mammography as a screening tool to the medical community in the 1950s. “If there was no such thing as mammography and you said, ‘how do we design a tool that finds cancer in women’s breasts?’ You would never design what we have now,” says Dr. O’Connell.
It’s not just the discomfort. Dr. O’Connell is also concerned about how “dense” tissue (ducts, milk glands, and supportive tissue) and cancer both show up white in a 2D mammogram. Dr. Kunjummen compares it with trying to see a snowball in a snowstorm. Tomography somewhat improves the ability to see cancer in dense breasts.
But what works even better is contrast imaging, in which cancer cells are visibly contrasted from healthy tissue. Remember the MBI I mentioned earlier? That’s one type of contrast imaging. Another is CT scans with nonionic iodinated contrast, a nonradioactive test that radiologists have been using to find cancer for over 50 years.
Dr. O’Connell is studying an application of this technology called dedicated cone-beam breast CT. It uses a special CT machine that images the breast alone, at a lower dose of radiation than a regular CT scan (the amount of radiation is a hair higher than a screening mammogram, but within range of a diagnostic mammogram). Ten seconds on each side, and cancers show up bright, Dr. O’Connell says.
“I think it’s going to be the next big thing,” Dr. O’Connell says. “No compression, women love that. Contrast, radiologists love that. So, it’s a winning combination.”
The FDA has approved dedicated cone-beam breast CT for diagnostic imaging, but it’s “not fully tested yet,” for screenings, Dr. O’Connell says. She is compiling research on the method to help lend it greater acceptability in the medical community.
Private insurers have been paying for this test, albeit at a low rate. The other hurdle is accessibility. You can’t convert a regular CT machine for this use — and the unique machines that do perform this kind of test are a rarity.
Still, the power to change that may be in our hands. Thanks to women’s grassroots advocacy, doctors in most states are now required to inform women when their screenings show they have dense breasts, so that patients can have informed conversations about their cancer risk and screening options. Dr. O’Connell believes the same kind of patient-driven advocacy could make dedicated cone-beam breast CT more accessible for cancer screening.
We have but to demand it.