Over the past couple of years there have been some significant developments in the area of breast cancer screening.
One of the new terms we hear quite frequently is “3D Mammography.” Many women are wondering what it is, and whether or not it’s better than its two-dimensional predecessor.
The researchers who pioneered 3D mammography, also known as tomosynthesis, or tomo, were looking for a way to get a 3D image of the breast without having to do an MRI (magnetic resonance image). MRIs are costly, time consuming, and, for most women, TMI— that is, too much information!—because they give a much more detailed diagnostic than clinically necessary.
The research doctors had the brilliant idea of taking hundreds of X-rays of the breast using the “thin slice” concept and compiling them into three dimensions, sort of like a digital flip book. The scientific theory of parallax (using different lines of sight to replicate size, distance, and position of objects) was used to model the technology, and a company called Hologic, Inc. developed the first FDA-approved system using this idea.
The technology allows little cancers to be spotted easily before they have time to grow large and spread outside of the breast. Tissue lying above a little cancer can no longer block it from view. Many experts anticipate that tomo will replace mammography as the standard of care.
The good news is that a recent study in the Journal of the American Medical Association (JAMA)demonstrated that the tomo technology enabled physicians to find more invasive cancers earlier.
Although it’s still premature, tomosynthesis looks very encouraging. In the study, tomo found 4.1 cancers for every 1,000 patients vs. 2.9 cancers for every 1,000 patients with digital mammography alone. That’s a more than 35 percent improvement in detection!
Keep in mind that even digital mammography is considered new compared with the standard hard film x-ray mammography, which is still widely in use.
The second important finding was that re-examination or “call backs” were needed less often, which means a reduction in the number of those dreaded telephone calls that start out with: “We need to take a few more pictures.” This saves lots of hours tracking people down to schedule additional appointments, doing tests, and interpreting results.
With traditional mammography, 107 out of every 1,000 women were called back; with tomo, only 91 out of every 1,000 women needed further study. That’s a drop of about 15 percent and translates into $1.2 billion savings in the United States alone, where about 38 million mammograms are done annually at an estimated cost of $8 billion.
Of the women undergoing tomo in the study, fewer needed biopsies. Of those who did need a biopsy, more women actually had cancer, and more of those cancers were the invasive ones that really needed to be detected at an early stage.
The study’s chair, Dr. Sarah Friedewald, remarked, “We found an increase in invasive cancers, the ones we worry about, that could be lethal.” She added: “We’re picking up the ones we want to be picking up. Overall, it’s very encouraging. We’re also reducing the number of people who have to come back.” So, even though more cancers were found, fewer additional biopsies were done, resulting in fewer “false maybes” and less needless worrying.
While tomo uses slightly more radiation than a traditional 2D mammography machine, the overall dose to a woman is still very low, at about 10 percent of the radiation one would be exposed to when flying from Los Angeles to Paris.
If there’s any bad news in all of this, it’s that the 3D mammography, or tomo, system costs about $500,000, about twice the cost of a standard digital mammography machine. Big hospital systems in densely populated areas will be able to get these machines sooner than smaller community or rural hospitals because they have the number of patients needed to support its cost. Obviously, if 100 women can have tomos on one machine each day, it is much more cost-effective than if five women come in for tomo per day in a rural area. Women who are at risk for breast cancer would be wise to travel to a place where they can have a 3D mammogram. It would be worth the trip.