It’s hard to understand opposition to screening middle-aged women for breast cancer. Mammography finds tumors early in over 80 percent of cases. The question is how to make the process safer, more accurate and efficient.
The optimal screening program should include ultrasound for women with dense breasts. The sound-wave test is good for detecting invasive cancers that are otherwise hard-to-spot in cloudy mammograms of dense breasts. The procedure should be covered by insurance and provided by expert radiologists who specialize in breast imaging.
The latest fuss about breast cancer screening has to do with this very issue. Some radiologists suggest it’s inadvisable or impractical to inform all women with dense breasts that an ultrasound might help clarify their cancer status, to know if they’re clear. Just last week, a perspective in a prestigious medical journal came down on legislation that would assure women have this information. The physician authors emphasize the role of “grassroots organizations and laypeople” in the push for women’s access to information about their breasts and supplemental studies.
The benefits of breast ultrasound – compared to other methods of breast cancer screening – are several. First, there’s no radiation. Zip. The sound-wave test is like an echocardiogram (to image the heart) or a sonogram many have while pregnant to check the fetus’s beating heart and developing limbs. In itself, ultrasound is safe and essentially harmless (without a biopsy, see below). And it’s inexpensive, especially as things go in radiology.
Courtesy of GE Healthcare: In the left panel, an ultrasound image obtained with GE’s Automated Breast Ultrasound (ABUS) system reveals a dark spot in the lower left breast (where the thin blue and green “crosshair” lines meet) consistent with an invasive malignancy. A bright yellow dot marks the patient’s nipple. In the right panel, a standard mammographic image of the same breast reveals dense tissue with non-specific calcifications.
Courtesy of GE Healthcare: In the left panel, an ultrasound image obtained with GE’s Automated Breast Ultrasound (ABUS) system reveals a dark spot in the lower left breast (where thin blue and green “crosshair” lines meet) consistent with an invasive malignancy. A bright yellow dot marks the patient’s nipple. In the right panel, a standard mammographic image of the same breast shows dense tissue with non-specific calcifications.
Low cost may be part of ultrasound’s problem – why some radiologists don’t favor mandatory notification. Today CMS pays in the range of $108 to $200 for bilateral breast ultrasound including fees for the doctor’s interpretation. Rates vary, depending on where the procedure is done. Typical reimbursement is around $150. The same government service pays around $540 for bilateral breast MRIs with interpretation.
Like other doctors, radiologists who publish academic papers on breast imaging may be influenced by idiosyncrasies in training, what machines their practices own or hospitals happen to have purchased, anecdotal experiences and personal skills. And there’s no getting around the profit motive, the possibility that some radiologists may deliberately highlight or subconsciously “see” the relative benefits of competing and higher-tech devices like MRIs.
The amount of work involved in performing a screening ultrasound is not trivial. It should take about 15 minutes (or longer) for a skilled radiology technician to collect images from each breast, and then it takes additional time for a doctor to review everything. As a physician with experience examining cells under the microscope, I know that the longer you look, the more likely you are to get an accurate sense of what’s going on. As an advocate, I want my physicians to spend the time necessary to inspect the scans carefully. So from my point of view, the more we pay radiologists to analyse these images (up to a point), the better.
$150 for the whole shebang – ultrasound machinery and physical office space, technician’s time, radiologist’s review, computers, documenting and communicating the results to other doctors and the patient – doesn’t cut it. Not even close.
So what’s the problem with breast ultrasounds? False positives are the main concern, as they are in breast cancer screening in general. For now, let’s forget about the angst and worry to which we women are reportedly so prone. Getting called back for an ultrasound or waiting three days (which shouldn’t happen) for a result may be stressful indeed. But that shouldn’t affect a rational woman’s decision to have a potentially curative or decades-adding, long term treatment-reducing procedure.
Let’s focus on the real false positives – when a doctor see a suspicious mark and performs a biopsy and there is no cancer. In the largest study of breast ultrasound for screening women of average risk for cancer with dense breasts, the investigators reported a false positive biopsy rate of just 2.4% (321 in 13,547 ultrasounds). That, in my view, is a very acceptable biopsy rate. And if you consider that most breast biopsies are now done with core needles in a radiologist’s office, it just shouldn’t be that big a deal.
In that analysis, Dr. Thomas Kolb and colleagues found that among women with dense breasts at average risk for breast cancer, ultrasound alone caught 25.5 percent (one in four) of cancers. Among women with very dense breasts (Bi-RADS category 4) in the analysis, ultrasound raised the sensitivity of screening from 47.6 percent by mammography alone to 76.1 percent. It’s reassuring that more recent data reveal yet higher capture rates of mammography followed by ultrasound in women, in the range of 90 percent; but those focus on women at high risk for breast cancer.
Now a radiologist or I might note that the Kolb study, however well-analyzed, was published back in 2002 – near-ancient history in the real world of digital imaging. The appropriate comparison in a future trial would involve 3-D mammograms. But the costs of clinical trials add up. I have doubts of their value, as by the time they’d be completed (and ideally, with survival information) for breast cancer screening, we’ll be another 15 years ahead.
At some point, common sense should enter the picture. In 2015 the added value of ultrasound seems clear enough. A pragmatist might even say this: let’s just go ahead and train radiologists to analyze ultrasounds carefully so that a woman in her forties, fifties and sixties who chooses to get screened for breast cancer – the most likely thing to kill her, absent a plague – and then offer that service, cover it, and monitor practitioners for competence.
A cynic or thoughtful analyst might consider that published ultrasound results are above-average; most radiologists aren’t so terrific at reading sound-generated breast images. In that case I suggest we teach doctors to do it better, and only let well-trained practitioners carry out these evaluations.
In 2014, Dr. Jean Weigert presented relevant data in a plenary presentation at the San Antonio Breast Cancer Symposium. She reported on the Connecticut experience with ultrasound in breast cancer screening after that state passed the first mandatory legislation regarding dense breast information (SABCS Dec 2014, Abstract S5-01). Her analysis was limited by its retrospective nature, but impressive by its volume, encompassing data from over 123,000 screening mammograms and 13,500 follow-up ultrasounds.
A striking find in Weigert’s study is that over time the radiologists got better at discerning cancer from other abnormalities on ultrasound. One measure of a test’s value is the positive predictive value (PPV). This statistic reflects the chances that an apparent abnormality is really a problem, like invasive cancer. In Weigert’s analysis of thousands of breast ultrasounds in Connecticut performed between Oct. 2009 and 2013, the PPV rose from 7.1 percent in the first year, to 6.1 percent, 8.1 percent and then 17.2 percent in the fourth year.
This improvement implies a learning curve, and suggests that doctors’ practice raises the accuracy and value of ultrasound in breast cancer screening.
“With experience we can better predict invasive cancer, by knowing how it looks by ultrasound,” Weigert told me at the December meeting. “The radiologists in Connecticut have gained confidence in it.” If this trend continues, radiologists will perform fewer needless biopsies. “Over time we got better at knowing when to do the biopsies and when we can hold off,” she said.
Another problem with ultrasound is the lack of skilled manpower and all the time involved. A possible solution would involve automated whole breast ultrasound technology, a topic I’ll review in an upcoming post.
You might consider the possibility, as I do, that if whole breast ultrasound screening turned out to be the best – safest, least expensive and most sensitive – way of catching invasive breast cancer early among women with dense breasts in their forties, fifties and sixties, perhaps women should be having ultrasounds instead of mammography, rather than as a supplement. I can’t fathom who would run that clinical trial. But I suspect a lot of women might register.
Finally, I’ll point to the need to make the screening process easier for women. Based on needless coding rules for some insurance and radiologists’ schedules, it’s unusual for a woman with dense breasts to simply get a mammogram in a specialist’s office, and then walk across the hall if needed to get an ultrasound, and then have a biopsy performed right then and there.
The hassle factor is a real deterrent for many women with jobs and other responsibilities. If the screening could be accomplished in one half-day, i.e. if the patient’s time were valued in the medical system, that would help a lot. And money. If insurance won’t cover the ultrasound, or if women with private insurance haven’t yet met their deductibles, they’re much less likely to go for early detection. Over the long haul, delaying detection may prove the costlier option.