More and more radiology center have 3D mammograms that compile more images and, supposedly, improve the chances of breast cancer detection, but there is little research on their effectiveness.
If they are found to be more effective, the new technology could become the norm, so US health officials and the National Cancer Institute are starting a huge study to tell if the newer, sometimes pricier, choice really improves screening.
Mammograms can save lives if they catch aggressive breast cancers early, but screenings can lead to over-diagnoses.
A 3D mammogram – marketed to catch more cancers – may only increase false positives and anxiety for women unnecessarily, rather than more effectively diagnosing the worst cancers, experts worry.
Traditional mammograms take two-dimensional images of breasts (pictured), revealing abnormal tissues or tumor. US health officials are launching a study to determine if newer 3D mammograms increase the chances of catching breast cancer over traditional methods
That trade-off is a key question as doctors begin recruiting 165,000 women nationally to compare potentially more beneficial 3D mammograms – known scientifically as ‘tomosynthesis’ – with standard two-dimensional digital mammography.
Two dimensional digital mammography takes images of the fronts and sides of women’s breasts.
Tomosynthesis takes multiple two-dimensional images and compiles them into more detailed 3D renderings of breasts.
Some insurers cover the newer screening process, but the 3D mammogram may come with up to $100 in extra charges to a patient.
The 3D mammograms have been marketed as being able to find more cancers.
‘But the idea isn’t so much finding more cancers as finding the cancers that are going to be life-threatening,’ said Dr Worta McCaskill-Stevens of the National Cancer Institute, which is funding the new research to tell whether the 3D scans truly pinpoint the tumors that matter most.
It’s one of the largest randomized trials of mammography in decades, and scientists designed the research to do more than answer that key 3D question.
They hope the findings will also eventually help clear some of the confusion surrounding best screening practices.
‘The most important thing about this study is that it’s moving us to individualized screening as opposed to what we have now, which is one-size-fits-all screening,’ predicted study chair Dr Etta Pisano, a radiologist at Boston’s Beth Israel Deaconess Medical Center.
‘We are going to have a much better understanding of how to screen women so that we do the least amount of harm.’
WHO NEEDS A MAMMOGRAM?
Guidelines on mammogram screening vary for women at average risk of breast cancer. (Those at increased risk, because of family history or genetics, already get different advice.)
The American College of Radiology recommends annual mammograms starting at age 40.
The American Cancer Society urges annual checks starting at 45 and switching to every other year at 55, although it says women 40 to 44 still can opt for a mammogram.
And the US Preventive Services Task Force, a government advisory group, recommends starting at age 50, with mammograms every other year. It, too, says 40-somethings can choose earlier screening.
Women at high risk for breast cancer are under-screened, and women at low risk are over-screened, a study reveals
Women with a 20 percent or greater risk of developing breast cancer based on their family histories, among other factors, should be given MRIs in addition to mammograms, according to guidelines from the American Cancer Society, the American College of Radiology and the Society of Breast Imaging.
If women have one or fewer first-degree relatives with a history of breast cancer, they are not supposed to be given additional MRI screening.
But a new study of nearly 350,000 American women found that these guidelines are not being followed.
In fact, the opposite is happening, the study published in the Journal of General Internal Medicine revealed.
About 83 percent of the women who were given the additional MRI screening did not meet the standards for being at high enough risk to warrant an MRI.
On the other hand, only a fraction of women who did meet the guidelines were given MRIs.
Of the women that were given MRIs despite lacking a family history of breast cancer, the study authors reported that many had less worrisome risk factors.
This group underwent MRIs ‘at many times the rate of other women, although the harms and benefits in this population are uncertain and the cost-benefit ratio may exceed established benchmarks,’ said lead author Dr Deirdre Hill of the University of New Mexico School of Medicine.
These women ‘may not be at substantially increased risk of cancers missed by mammography and thus may not be the groups in greatest need or who would receive the greatest potential benefit of screening MRI,’ she added.
WHO SHOULD GET A 3D MAMMOGRAM?
Standard mammograms take X-rays from two sides of the breast.
With tomosynthesis, additional X-rays are taken at different angles – not truly three-dimensional but a computer compiles them into a 3D-like image. First approved by the Food and Drug Administration in 2011, they’re not yet standard in part because of questions that the new study aims to answer.
Some studies have found tomosynthesis detects more cancer with fewer false alarms; they’re often advertised as particularly useful for younger women’s dense breasts.
DECIDING WHAT KIND OF MAMMOGRAM TO GET, AND WHEN
Understand that mammograms come with pros and cons, and weigh them, said Dr. Otis Brawley, the American Cancer Society’s chief medical officer.
Breast cancer is far less common at age 40 than at age 50 and beyond. After menopause, tumors tend to grow more slowly and women’s breast tissue becomes less dense and easier for mammograms to provide a clearer image.
For every 1,000 women screened every other year until their 70s, starting at 40 instead of 50 would prevent one additional death – but create 576 more false alarms and 58 extra unneeded biopsies, the task force estimated.
Also, two extra women would be treated for tumors that never would have become life-threatening – that over-diagnosis problem.
As for what type to choose, some insurers, including Medicare, cover the 3D version, and a small number of states mandate coverage. Other insurers may require women to pay $50 to $100 more out of pocket. Whoever ultimately pays, extra time to analyze the scans adds to the cost.
THE NEW STUDY AIMS TO GIVE BETTER GUIDANCE
About 100 mammography clinics across the US, and a few in Canada, will enroll healthy women ages 45 to 74 who already are planning to get a routine mammogram. They’ll be randomly assigned to get either the regular or 3D version for five years. Most will be screened annually but post-menopausal women who don’t have certain cancer risk factors will be screened every other year.
Researchers will track every woman’s results including samples from biopsies plus genetic and other tests, as well as how any cancer patients fare. The giant database hopefully will help them tease out more information about which women benefit most from what type and frequency of screening.
‘Mammography has been provocative over many decades. It’s important that women have a better understanding of how mammography is important for them based upon their age and other risk factors,’ said McCaskill-Stevens.