New Screenings
for Breast Cancer

by Sandra Gordon

Victoria Kovacs Myers, 41, a sales manager in Hilton Head Island, South Carolina, and mother of two, was 37 when she got a mammogram to investigate a lump in her right breast. It proved to be a benign cyst. Three years later, when she turned 40 and went to her doctor for her first routine mammogram, nothing beyond the original cyst showed up. But just to make sure the cyst hadn’t changed, her doctor suggested an MRI (magnetic resonance imaging). An emerging technique in breast-cancer detection, MRI is now considered a useful add-on to mammography to screen women with dense breasts—which was the case with Kovacs Myers—or others who are at high risk for the disease.

Dense breasts contain more glands, ducts and connective tissue than fat. Breasts tend to be denser during a woman’s reproductive years; density makes it harder to detect suspicious lumps on a mammogram. Also, older women on hormone therapy often maintain high breast density.

“My right breast, the one I was worried about, turned out to be fine, but the MRI showed that in my left breast I had a tumor in excess of 5 centimeters that my mammogram and a clinical breast exam had missed,” Kovacs Myers says. (The disease is considered to be caught early when tumors measure 1 centimeter or less and have not metastasized or spread.) By the time it was detected, the invasive tumor had spread to 20 out of 26 lymph nodes on her left side. Kovacs Myers quickly underwent a lumpectomy to remove the harmful tissue and had chemotherapy and radiation. It was a close call.

“MRI saved my life,” she says. “I would be dead by now without it.”

A yearly mammogram is still the gold standard for breast-cancer screening and detection for women over 40 (or earlier for those at high risk for the disease). It’s the only test that has been scientifically proven to save lives. Still, it’s not always able to spot the disease in its early, potentially most treatable stages, especially if a woman has dense breasts.

The odds that a mammogram will fail to detect a cancerous lesion is small but significant. In general, the test is 83% sensitive, meaning that in large populations of women screened with mammography, it can miss cancer 17% of cancers. “But in women with very dense breasts, mammography will miss cancer 58% of the time,” says Thomas Kolb, MD, a breast-cancer radiologist and leading ultrasound researcher in New York City.

Breast density depends in part on hormonal status, not necessarily weight, which is why premenopausal women are more likely to have dense breasts than postmenopausal women. Genetics also plays a part. It’s estimated that 62% of women in their 30s, 56% in their 40s, 37% in their 50s and 27% in their 60s have breasts that would be recognized as dense.

Ask your doctor for your breast-density measurement. It should be stated on your mammography report in one of four categories ranging from ‘fatty’ to ‘extremely dense.’ Anything other than ‘fatty’ means a mammogram may be obscured to some degree.

Mammography also tends to miss lobular carcinoma in situ (LCIS), possible tumor precursors that mark women as high risk for breast cancer and lack the calcifications (calcium deposits that may indicate cancer), mass or density that would show up on a breast X-ray. Fortunately, in addition to MRI, there are other new tools that, used with a mammogram, serve to give a more precise diagnosis. “If you’re at high risk or you have dense breasts, you may be a candidate for one or more of them,” says Cheryl Perkins, MD, the senior clinical advisor with the Susan G. Komen Breast Cancer Foundation, in Dallas, who advises you to ask your doctor about them. Here are four that may give you a clearer picture of your breast health—and could possibly save your life.

Digital Mammography

This cutting-edge X-ray test can be used in place of a standard mammogram and is performed in the same way as the traditional screening tool—your breasts are compressed between two plates as whole images are taken. But instead traditional X-ray film, electronic detectors convert X-rays into electric signals (much like a digital camera does), which can be used to produce images on a computer screen. These pictures can also be printed on special film.

Pros & Cons: Studies show that digital mammograms aren’t any more sensitive in diagnosing breast cancer than conventional mammograms; however, doctors who use the technology feel it has distinct advantages. “We have been using digital mammography as our primary screening tool since 2000, and I feel that it’s superior to traditional film,” says Ulana Suprun, M.D., vice medical director of Medical Imaging of Manhattan.

“Radiologists can manipulate a digital image and see contrasts in tissue density more clearly,” says Dr. Suprun. That may ultimately reduce the need to call patients back to decipher questionable findings, an inconvenient and anxiety-producing process. In fact, in a study by Sughra Raza, MD, director of the Women’s Imaging Program at Brigham and Women’s Hospital, in Boston, involving more than 12,000 women, digital mammography reduced the call-back rate by 12 fewer women per thousand, compared with conventional mammography, which is statistically significant. Digital X-rays, unlike film mammograms, can also be sent from one computer to another, making consultation among physicians, reviews of earlier mammograms and second opinions just a mouse click away.

It’s estimated that more than 90% of mammography centers across the United States still use conventional film mammography. “But as digital technology improves and equipment becomes more affordable, digital mammography will be the wave of the future,” says the Komen Foundation’s Dr. Perkins.

Should You Ask for It? Currently, because the equipment is expensive, digital mammography is only available at major breast centers, which tend to be located in major cities. When you schedule your next mammogram, it’s worth asking whether the center offers digitals and, if necessary, traveling farther to lower your risk of needing a repeat screening, says Dr. Raza. The screening test is typically covered by insurance, but check your policy to be sure.

Computer-Aided Detection (CAD)

With this emerging technique, a computer scans a digitized mammogram or a conventional one that has been digitized and flags areas of concern, enabling a radiologist to take another look and decide whether the computer markings warrant further action. “It’s like having an automatic second opinion,” says Mitchell D. Schnall, M.D., Ph.D., deputy chair of the American College of Radiology Imaging Network (ACRIN), a research group in Philadelphia funded by the National Cancer Foundation.

Pros/Cons: Two studies reported that CAD helped radiologists detect 20% more cancer than mammography alone. But the research also suggests that CAD caused radiologists to disregard their own findings if the computer didn’t highlight them.

Because CAD tends to also mark lesions that aren’t cancerous, such as bunched-up tissue, benign lymph nodes and benign calcifications, the rate of false positives is high, especially in screening a population of healthy women. Less than 1% of findings marked by CAD turn out to be cancer.

Still, that doesn’t necessarily translate to unnecessary biopsies. “Most of the time, we take a quick look at CAD markings on mammograms and discount them,” says Stamatia Destounis, MD, associate clinical professor at the University of Rochester and staff radiologist at the Elizabeth Wende Breast Clinic, also in Rochester, New York. “But on occasion, it does mark something we need to pay attention to.” CAD is widely available at mammography centers and university and hospital-affiliated breast clinics across the country and is generally covered by insurance.

Should You Ask for It? Although CAD isn’t a perfect tool, “it should be the standard of care for every woman who gets a mammogram,” says Dr. Destounis, who has been using CAD since 2000. “But there’s definitely a learning curve and a lot depends on the expertise of the radiologist reading your mammogram.” To reduce your risk of unnecessary additional testing, such as biopsy, find a facility with mammography-certified technologists and trained radiologists who have been using CAD for at least a year.

Screening Ultrasound

During this test, a handheld device that resembles a microphone, called a transducer, is moved over each breast to transmit sound waves, which “see” through the skin into the body. The waves appear as images on a computer monitor, which can be recorded and reviewed later. The painless procedure takes five to 15 minutes in the doctor’s office.

Pros & Cons: Studies show that compared with mammography alone, adding a screening ultrasound can nearly double the detection rate of cancer in women with denser breast tissue. “It’s the single most effective tool to find additional cancers above and beyond what mammography misses,” says Dr. Kolb.

Experts don’t recommend using ultrasound without mammography, however, unless you’re under 30 and you have a palpable lump or nipple discharge. In such cases, ultrasound is typically used first, possibly in lieu of mammography, because less-mature breast tissue is more sensitive to the potential cancer-causing effects of low-dose radiation. Ultrasound also tends to miss fully half the time a very early form of cancer that starts in the milk duct, known as ductal carcinoma in site (DCIS), says Wendie Berg, MD, PhD, a breast-imaging consultant in Baltimore and ACRIN-affiliated researcher. And screening ultrasound can sometimes result in a false-positive reading. Several individual studies found it involved a 2 to 6 percent risk of having unnecessary biopsy or aspiration (the removal of breast fluid or cells using suction). A large clinical trial sponsored by the Avon Foundation and the National Cancer Institute to investigate this screening technique is currently under way.

Should You Ask for It? Ultrasound isn’t the standard of care for screening purposes (though it is used for diagnostic tests). “But patients may want to ask for it in addition to mammogram if they have dense breast tissue,” says Dr. Berg. If you’re at high risk but you don’t have dense breasts, a mammogram should suffice. Because screening ultrasound is still in its infancy, insurance providers don’t typically pay for the test, which costs from $75 to $150, though more states now require that it be covered (check your policy). Also, ultrasound is not as stringently regulated as mammography: For instance, radiologists aren’t mandated to read a certain number of screening ultrasounds per year to keep their skills sharp. For better accuracy, “seek out a technologist or physician who does a minimum of five screening breast ultrasounds daily,” Dr. Kolb advises.

MRI (Magnetic Resonance Imaging)

This tool employs magnetic and radio waves instead of X-rays to create high-definition cross-sectional images of breast tissue. For the test itself, the patient is injected with safe, nonradioactive contrasting salt solution in the arm, then lies facedown on a table with both breasts positioned into cushioned coils that contain signal receivers. The entire bed is then sent through a tube-like magnet. In areas where there might be cancer, the contrasting agent pools and is illuminated on computer-generated images. The machine is noisy, so it’s important to wear ear protection.

Pros & Cons: Several studies have shown that MRI finds 2% to 6% more cancers than mammograms and clinical breast exams in high-risk women. A woman is considered high risk if she has a strong family history (a mother or sister diagnosed with breast cancer before age 50) or carries a genetic mutation (BRCA1 or BRCA2), among other factors. Talk to your doctor about whether your risk of breast cancer indicates you may benefit from MRI screening in addition to mammography. Like ultrasound, MRI can’t detect calcifications (a frequent sign of DCIS), which is why it’s used as a complement to mammography, not a replacement. MRI has also a significant risk of false positives. Screening breast MRI costs $1,000 to $2,000, though many insurance carriers now cover it.

Should You Ask for It? “Even if you have as little as a 2% risk of breast cancer over the next five years, talk to your doctor about adding MRI,” says Dr. Berg. MRI breast-imaging centers are springing up across the country, but the technology isn’t federally regulated or as widely available as ultrasound. Know-how counts, so “seek out practitioners with more experience,” says Etta Pisano, M.D., professor of radiology and biomedical engineering at the University of North Carolina, in Chapel Hill. It’s also important to seek out a facility that has MRI-guided biopsy capability, so a tissue sample can be retrieved for diagnosis at the time of your scan if a questionable mass is spotted. •

from the May-June 2006 issue

Mammograms can miss 17% of cancers. But in women with very dense breasts, it can miss cancer 58% of the time.
Are Better Screening Tools
Coming Soon?

Research is constantly underway for methods that may help spot breast cancer earlier. Tomosynthesis, a 3-D X-ray technique that takes clear image slices of breast tissue, is one of the technologies that may be available in the near future. The breast is compressed, as with conventional mammography, and a series of images are obtained from multiple angles. (In contrast, mammograms produce two-dimensional images of the breast so that tissues all the way through are superimposed on one another, which can make deciphering abnormal tissue from regular tissue and breast structures difficult.) “Tomosynthesis is a better mammogram,” says Daniel Kopans, M.D., professor of radiology at Harvard Medical School, in Boston. It is expected to simultaneously increase the rate of breast-cancer detection and reduce the risk of false positives. Pending FDA approval, tomosynthesis is expected to be available to the public within two years.

Two techniques, positron emission tomography and scintimammography, involve injecting a radioactive substance into the body to detect cancer at the molecular level before it can be felt or seen by X-ray. Other experimental techniques, such as microwave imaging and computed tomography laser mammography, employ low-energy electromagnetic waves or light to differentiate tumors from healthy breast tissue. Cancerous areas are thought to transmit microwaves or absorb light differently than benign growths. These imaging techniques aren’t available outside of a clinical trial yet and still may be years away from being considered a standard of care.

Another promising tool is a simple hand-held optical device that may let women screen themselves for breast cancer in the privacy of their own homes. This tool, which has yet to be named, uses near-infrared light to measure blood oxygenation and blood volume of breast tissue. Areas with unusual amounts of deoxygenated blood set off a sound, signaling a possible tumor. “This tool is an early warning that something is amiss in the breast,” says the device’s creator, Britton Chance, M.D., professor emeritus of biochemistry, biophysics and radiologic physics in Philadelphia. Women then take the device to their doctor to assess the recorded information. If this invention makes it to market, it’s expected to cost less than $100. Women at high risk for breast cancer might use the device once a month, while women at average risk, every six months, says Dr. Chance. It may be available within two years.