Breast health

Mammograms — what’s best for you?

by Dixie Mills, MD, FACS

New recommendations for mammogram screening are raising questions for women everywhere. It’s important for every woman to understand the benefits and limitations of screening mammography, so that she can make the choice that’s right for her. Here are the sections in this article:

• What is a screening mammogram?
• The controversial mammogram — objections to mammography
• The “picture problem” with reading mammograms
• Alternatives to mammography
• The bottom line on mammograms

Many women were shocked to hear the report recommending a change in mammogram screening guidelines. After being encouraged to get a mammogram once a year starting at 40 and to check our breasts monthly, it feels like we’re breaking the law, being deprived, or missing out on some essential rite of passage if we don’t follow these rules. But a recent report prepared by an independent panel of experts (the US Preventative Services Task Force, or USPSTF) and published in the Annals of Internal Medicine, recommends that most women put off mammograms until age 50, and get them every other year instead of annually.

I’m the first to admit that this topic is confusing: there is no one simple message when it comes to mammography. We’ve been told it save lives, then we hear of a woman who had a clean mammogram three months prior to finding a lump in her breast and she’s gone in a year. The fact is, having annual mammograms will not prevent you from getting breast cancer — unfortunately, mammograms don’t act like brushing and flossing our teeth do to prevent cavities and gum disease. Mammography will detect some pre-existing lumps, but the technology (and the experience) is far from perfect. And though many don’t know it, mammograms do come with some very real risks.

Though early detection through mammography is still the most widely available tool we have for beating breast cancer, especially for women at elevated risk, mammography is only a supporting player in good breast health, not the lead role. At Women to Women we put as much if not more emphasis on optimal nutrition, exercise, and a healthy lifestyle. In terms of preventing breast cancer, there is a lot of hopeful research pointing to the benefits of daily exercise, maintaining a healthy weight, eating soy, and supplementing with fish oil, iodine, and indole-3-carbinol (a compound found in cruciferous vegetables like broccoli).

So what should you do about mammograms? Let’s put the latest information into perspective, so you can work with your practitioner and make an educated decision for yourself.

The controversy over mammograms

For every woman I see who declines mammography outright, I see one who wants a mammogram every month. Both ends of the spectrum are probably a bit too extreme. But all things being equal (age, family history, general health), which of these patients is more likely to die from breast cancer — and whom does the mammogram benefit?

Over the past 30 years, mammograms have been shown to decrease breast cancer deaths in women over 50 years of age by 30%. But a benefit for women in their 40’s was never clearly demonstrated, begging the question: When is the best time to start — age 40 or 50?

These are all million-dollar questions, because much of the controversy swirls around the numbers, and millions of women are asking them.

The USPSTF now recommends that unless women have specific risk factors, they should start mammography screening at age 50 and obtain a mammogram every two years, rather than yearly. The Task Force also recommends women discontinue screening mammograms at age 74. Researchers found that not only did the great majority of women gain no benefit from yearly screening mammograms, some incur harm from them. Other recent studies have pointed to overdiagnosis and the emotional toll of false-positives as drawbacks to yearly mammograms.

But other groups, including the American Cancer Society, the American College of Radiology, and the Society of Breast Imaging continue to recommend annual mammograms starting at 40. Let’s look at what’s behind the new USPSTF recommendations.

• New statistical data from computerized models and a number of well-designed, carefully conducted studies, each with over 10 years of follow-up, showed that mammogram screening exams would prevent only 1 death in nearly 2000 women aged 40-49, while there would be 99 false-positive results per 1000 screening exams.
• The hazards from radiation exposure from extra images are also part of the added harm to this age group.
• Likewise, the studies and statistical analyses showed no difference in survival among women 50-69 years of age who were screened every 1 to 2 years.

These new recommendations are actually in line with the protocols followed by most European countries for the last 10 years — and most of Europe does not have higher rates of death from breast cancer than the US.

In another interesting study reported back in 2005 in the Journal of the National Cancer Institute, researchers looked retrospectively at almost 4000 women in the US between the ages of 40 and 69. Much to the surprise of the authors, the study found that women who underwent regular screening died at the same rate as those who declined mammograms. Their results suggested there may be some benefit to regular screening for women who are at an increased risk for breast cancer due to family history or prior atypical breast biopsy. (See the NCI’s free, interactive Breast Cancer Risk Assessment Tool. As recommended, be sure to discuss the results with your healthcare provider.)

I think that most women had assumed that the benefit of annual screening was much stronger and that mammograms were far more effective. Unfortunately, mammograms don’t provide the direct protection and safety of seat belts or motorcycle and bicycle helmets. However, if you multiply the number of cancer deaths averted by millions of baby-boomer women, these small percentages still add up to thousands of lives saved. What’s a woman to do?

So why not err on the “safe” side?

I heard one 59-year-old woman recently say, “I’ve been getting a mammogram every year since I was 39, so why stop now?” Despite the news that the death rate from breast cancer has fallen somewhat, the incidence of breast cancer is still rising, albeit a bit more slowly. By now, we all have known or have had a friend who has been diagnosed with the disease, and more and more of us know someone who died from breast cancer at a young age. Most women are willing to undergo whatever testing they can to beat the odds of this frightening disease.

So why am I hearing from more and more patients: “Do I really need that mammogram?” Aside from the debate about whether mammograms really prevent breast cancer deaths, there are some downsides to the test.

• Mammograms are uncomfortable (and for some women, outright painful). When my patients relate some of the humiliating experiences they’ve had while getting a mammogram, I don’t blame them for never wanting to go back — whatever the risk. Our breasts are very personal and many of us aren’t that comfortable touching them ourselves, let alone having them manhandled by an x-ray machine or a bossy technician!
• Mammograms come with high levels of false positives for younger women. It is estimated that about 10% of mammograms are read as false positives, depending on the age of the woman, the center, the radiologist, the equipment, and the protocol used to read the images. This leads to increased anxiety and dread in many women.
• Mammograms can lead to unnecessary procedures. Nowadays, mammograms lead to the diagnosis of more cancers, but particularly in situ cancers, which are generally noninvasive (not associated with an increase in mortality). Are they actually saving lives? Not as many as you may have thought. And many women end up having unnecessary additional radiation and invasive surgical procedures.
• Mammograms expose us to radiation. Epidemiologists have calculated that cumulative radiation exposure from yearly screening mammograms commencing at 40 could cause a net overall increase in cancer deaths. As always, there’s a risk-to-benefit ratio to consider, and the younger we are when exposed to radiation, the more sensitive our tissues.
• And then there are the cancers that are missed — up to 30%. Many women have a false sense of security after being told that their mammogram was normal only to be shocked to find a malignant lump a couple months later. For more on this, see discussion of the picture problem below.

The experts really did think mammograms would help us detect cancers earlier and save lives — and initial studies showed it did just that. As healthcare practitioners, we all bought into the early detection hypothesis, but we now know that there are more than five types of breast cancer. Some grow fast and act aggressively in the body, while others are slow growing. Some types act in ways that make finding them early on very helpful, while others do not. And we’re even discovering that some forms of cancer might be better off left undetected!

As I mentioned before, mammography is still the best tool we have for detecting early breast cancer, especially if you are known to be at heightened risk. But I hope the women who want to continue with their yearly mammograms out of habit or because they feel it is safer will discuss this with a trusted healthcare provider, and balance risks and benefits according to their own health history and beliefs.

Mammography and the “picture problem”

There are reasons why mammograms come with so many false positives and false negatives. A number of difficulties exist in getting a quality image of the breast, otherwise known as what best-selling author Malcolm Gladwell calls the “picture problem.” In the 2�D world of screening mammography, two black-and-white pictures of each breast are taken. These contrasting views provide some dimension, but little more than what is up, down, medial, or lateral.

Up until the 1960’s basic x-ray equipment was used to look at the breast and chest cavity. Compression imaging was introduced in the early 1980’s, which simplified the process and provided a better view — opening the door to mass screenings. While the radiation doses have decreased significantly since the 1960’s, not much else has changed.

Frankly, I’m surprised we’ve progressed from color television to high-definition TV while women’s breasts are still being imaged with black-and-white x-rays. Even our children’s video games have better depth and detail than the average mammogram!

Mammograms are clearest when imaging fatty breasts, which are naturally more prevalent in older women — usually post-menopausal women not on HRT. Higher hormone levels naturally cause breasts to be more fibrous and harder to read on a mammogram — or “dense.” (Perhaps this is the reason mammograms are more beneficial for older women). How your breasts feel does not always correlate with how they look on mammograms.

A textbook cancer — or as some doctors would say, one that a medical student could see — would show up on a mammogram as an irregular white shape, often called a “mass” or a “nodule.” “Nodes” are lymph nodes, the little shapes generally seen higher up in the armpit on films. The white shape shows up best on a background of gray or black, which is fat on a mammogram.

Dense breasts contain a lot of perfectly normal fibroglandular tissue that shows up as white areas on a mammogram. Part of the “picture problem” with mammograms of dense breasts is that the white areas created by those fibrous tissues can conceal a small cancer — like trying to find a polar bear in a snowstorm. For more information, see our page on dense breasts and “dense mammograms”.

It’s ideal when women with family histories or other high-risk factors are screened at a breast center where they’re informed of their results quickly and, if necessary, additional imaging carried out right away, or they are at least scheduled right away for follow-up, so the period of waiting without knowing is minimized. I’d like to think all women will have their testing done this way one day!

Because there’s a lot of variation in how mammograms are read and the element of both human and technological error is considerable, it’s a good idea to get a second opinion whenever there’s a questionable result.

What are the alternatives to mammography?

There are other forms of breast imaging in use and in development today that provide an alternative picture of breast tissue. Some of these imaging techniques are still experimental, and some are of limited availability, and some are considered more appropriate for diagnostic rather than screening purposes. But you may be able to request an alternative, if your mammograms are dense, you’re otherwise at higher risk, or you do not believe in or want to have mammography.

Sometimes women are recommended to have ultrasound screening or magnetic resonance imaging (MRI) of their breasts in follow-up to screening mammography. Because these techniques are generally more costly, not all centers provide them and not all insurance policies cover them, so you may want to ask your healthcare provider to discuss all your options — and verify your insurance coverage beforehand if cost is a consideration.

Many institutions are converting to digital rather than film mammography, where the images are digitized (like a digital camera), which allows them to be readily called up for review on a high-resolution monitor. It also allows the degree of contrast and some other image qualities to be manipulated, and computer programs have been developed to assist in analyzing the tissue changes that take place over time. Digital mammography offers some significant benefits over film for certain groups of women — premenopausal women and women with dense breasts, according to a study published in NEJM. Another benefit to digitizing images is that it allows a radiologist to view your files from a remote location (helpful for second opinions). False positives and false negatives are still possible, however, so the benefits aren’t clearcut, and digital mammography is still not widely available in some areas.

Thermography, or heat detection, is an old method which newer technology is bringing back. At this point, very few large studies have looked at thermography. I’ve encouraged women interested in the test to find an experienced institution that will correlate their findings with other testing. I personally have seen false positive and false negative results with different practitioners using different types of cameras. However, if you know of a healthcare provider accredited in thermography, it might be something to try.

I always joke that I may be able to become the curator of a mammogram museum before I die. Technology is advancing by leaps and bounds and breakthroughs that make our current machines obsolete are sure to occur!

What is the bottom line on mammograms?

Mammography is definitely not as good as anyone thought it could be or as beneficial as we’d like it to be, but I think we are still better off than we would be without it. I think it’s prudent to follow the new guidelines and get a mammogram every other year between the ages of 50 and 74, but it should always be a choice, not an obligation. If regular mammograms go against your belief system, reason, or common sense — don’t worry. You will not be arrested or ticketed and your likelihood of dying from breast cancer is still very small if you decline the test.

There is just no definitive answer on mammograms. What you should take into account is your own individual health picture: your risk factors, age, breast density, and your threshold for anxiety and risk. Some women may be comfortable getting a mammogram only a couple times in their 40’s and 50’s; others may need more regular reassurance.

If you do decide to get a mammogram, I list some suggestions to get the most out of it on my blog post, mammogram myth.

My dream is that in the near future there will be a simpler, better way to screen women’s breasts. The good news is that researchers are now studying markers of cancer (or risk of getting it) in nipple aspirate fluid, blood, saliva — even urine! And there are many things we can do to create better breast health (see breast health tips, above). We need to focus our efforts to find the cause or causes of breast cancer, and prevent it altogether. Check out the Army of Women for more information. Maybe I will get to be the curator of a mammogram museum when I retire!

Related to this article:

References & further reading on mammograms

 

Last Modified: 09/10/2012
Principal Author: Dixie Mills, MD, FACS