Tomosynthesis, or 3 dimensional mammography may sound like a new breast screening test, but it’s been available since February of this year. This new detailed mammography exam finds more cancers that would otherwise have been missed. The company, Hologic Inc., from Bradford, Mass. also claims it causes fewer false alarms. Even though this technology looks to be better for all women, which showed a 47% increase in cancer detection in an ongoing study of some 25,000 women, it looks especially promising for women with dense breasts.
Research has indicated that women with dense breasts are at higher risk for breast cancer than those with less dense breast density. It is unsure whether it is due to something associated with specific breast tissue itself or that mammograms just cannot detect deep tumors. A 3-D mammogram may reduce the potential risk factor for these women by being able to get detailed data using 50-60 razor thin slices for each view showing what breast tissue looks like at various depths.
Laurie Margolies, director of Breast Imaging at Mount Sinai Medical Center in New York says that 3-D mammograms could save lives by finding cancers earlier where women could possibly forego chemotherapy or at least avoid higher doses.
Even though this technology looks promising, there is a downside. The cost is higher, and it delivers twice as much radiation as traditional mammograms. This double radiation dose could potentially cause cancer in 1 in 1000 women who get 3-D mammography annually from age 40 until 80 instead of the standard exam according to the FDA.
The 3-D mammogram also includes a standard 2-D mammogram and has a woman under compression for approximately 48 seconds, compared with about 20 seconds for a standard exam. Ouch!!
But are we looking and searching for breast cancers that would otherwise do no harm?
So even if we use 3-D screening exams that finds 47% more cancers, how many of those cancer treatments would be unnecessary? In one article in Norway, epidemiologists estimated that 15% to 25% of breast cancers found by mammograms were being treated unnecessarily. The study in the Annals of Internal Medicine in April 2012 estimated that for every 2,500 women getting mammograms over 10 years, one life was saved from breast cancer but 6-10 women were subjected to surgery, radiation and/or chemo unnecessarily. Some believe that fewer mammograms would reduce the number of small early cancers. That’s the rationale of the U.S. Services Task Force whom recommended that women discuss with their doctors how often they should screen for breast cancer. They changed their recommendations from every year to every 2 years over age 50 and recommended to limit mammograms even more for women in their 40’s due to increases in false positive results (abnormal mammograms that are truly negative). This 3-D mammogram claims to reduce these anxiety-producing recalls where women are told to return for more testing or even biopsies.
Currently there is no way to tell which patients diagnosed with breast cancer could forego treatment. And for now, there are no doctors that would offer women the option of doing nothing. But there has been progress in analyzing individual breast cancers and specifying treatment to each individual woman. The most commonly used test is the Oncotype DX, which analyzes 21 genes. This test determines how likely the cancer is to return in 10 years and whether the woman would benefit from surgery as well as chemotherapy and radiation.
I believe mammograms are important no matter which type you choose. But it’s important to be informed and know the truth about over-diagnosis, especially with more sensitive tests like the 3-D mammogram and breast MRI screening. I only hope that someday soon we find additional tests that can better predict which breast tumors are worth treating and which are harmless.
Reference: Johannes, L. “Is a 3-D Mammogram Better At Avoiding False Positives?”- WSJ.com, 10/12/2012
Beck, M. “Can There Be Too Much Breast-Cancer Treatment?”-WSJ.com, 9/2012