The Downside of Mammograms

on April 6, 2017 by Chris Kresser

Mammography has been the medical industry’s “gold standard” breast cancer screening tool for nearly four decades, and the procedure has been pushed on women with great zeal by physicians, public health programs, and cancer organizations. However, mounting scientific evidence indicates that mammography may not only be far less effective than we have been led to believe, but that it also has numerous drawbacks that are affecting women on a massive scale. Read on to learn about the major drawbacks of mammography, what the research recommends for breast cancer screening, and about promising breast cancer detection alternatives.

A brief history of mammography

Mammography screening for breast cancer was first introduced in the late 1970s, and by the early 1980s, it had been widely incorporated into clinical practice. Prior to the widespread use of mammography, breast cancer detection tests were primarily based on breast self-exams and clinical breast exams performed by physicians. In the very early days of mammography, this test was used only in women at high risk for breast cancer; this included women who had a previous history of breast cancer, had a mother or sisters with breast cancer, or were over 50 years of age.

Fast-forward to the present day, and it is quite apparent that the use of mammography has increased dramatically. According to recent data, 66.8 percent of women over the age of 40 have had a mammogram within the past two years, an average of 15 million physician office visits have taken place per year in which a mammogram was either ordered or performed, and an additional 3 million outpatient visits have ordered or performed mammograms (1).

Despite this massive increase in the use of mammography, there is a substantial body of research indicating that the widespread, overenthusiastic practice of mammography over the past few decades has had little to no effect on breast cancer mortality rates (2). In fact, the research indicates that mammography screening may do more harm than good. Mammography has demonstrated a number of adverse effects, including breast cancer overdiagnosis, unnecessary breast cancer treatment, undue psychological stress, excessive radiation exposure, and a serious risk of tumor rupture and spread of cancerous cells (3)(4).

Could mammography screening do more harm than good? #breastcancer

Mammography screening leads to breast cancer overdiagnosis and overtreatment

A 17-year study conducted in Denmark from 1980 to 2010 measured the incidence of advanced (> 20 mm in size) and nonadvanced (≤ 20 mm in size) breast cancer tumors in women ages 35 to 84 who either had received regular breast cancer screening over the years or had not received screening. If mammography was effective at reducing rates of advanced breast cancers, a reduction in the incidence of advanced tumors in the women who received the screening should have been observed. However, no difference was found in the incidence of advanced tumors between the screened and unscreened groups. In addition, significant overdiagnosis of breast cancer was found in the screened group—approximately one out of every three invasive tumors and cases of ductal carcinoma in situ (DCIS) was found to represent breast cancer overdiagnosis. This meant that, due to screening mammography, healthy women were diagnosed with breast cancers. These women subsequently had to deal with the severe psychological distress of a cancer diagnosis, as well as the numerous physical harms of cancer treatment, when in fact their tumors were not cancers that necessitated treatment at all (5).

A systematic review published several years prior found very similar results; in the United Kingdom, Canada, Australia,  Sweden, and Norway, the overdiagnosis rate in organized breast screening programs was 52 percent, meaning one in three cancers in the screened population was overdiagnosed (6).

Further research has found that mammography screening has led to an increased detection of small tumors, but only a modest decrease in the incidence of advanced tumors. Many of the small tumors being detected by mammography represent breast cancer overdiagnoses. These small tumors are growths that, if left alone, would never progress to an advanced stage. However, mammography is diagnosing them as cancer, which is in turn causing countless women to be convinced to undergo cancer treatment, with all its harm and side effects, and without any benefit. In regards to the modest reduction in large breast tumors noted above, this reduction has been attributed to improved breast cancer treatment, not to screening mammography (7).

Mammography selectively detects more favorable tumors

Mammography has a tendency to selectively identify tumors with favorable molecular features, which are features that make breast cancer treatment easier, offering a better prognosis. This is due to the fact that tumors with favorable characteristics tend to grow more slowly, so there is a larger window of time in which they can be detected by screening mammography. When screening mammography is used, these favorable tumors tend to be diagnosed long before they would begin to cause symptoms. This phenomenon is called length-bias sampling and refers to a statistical distortion of results that occurs when screening identifies disease cases before the onset of symptoms, making it appear as though survival time is increased for the particular disease due to screening. However, favorable tumors typically respond to treatment equally effectively at clinical presentation (when symptoms appear) as they do when diagnosed via mammography, so earlier detection through screening mammography does not translate into a reduction in breast cancer mortality (8).

Breast tissue density affects the ability of mammography to successfully detect tumors. Low-density breast tissue makes it easier for mammography to visualize tumors than does higher-density breast tissue. In the fatty breast, mammography sensitivity is 98 percent; in the very dense breast, the sensitivity goes down to as low as 48 percent (9). This is a significant issue because in postmenopausal women (the subgroup of our population that undergoes regular mammography screening), high-density breast tissue is associated with an increased risk of breast cancer as well as with the presence of tumors with more aggressive characteristics, such as larger tumors and estrogen receptor-negative tumors. The relative ease with which mammography detects favorable tumors has led to an overestimation of the effect of screening mammography on breast cancer mortality (10).

Radiation from mammography may increase risk of breast cancer

The cumulative effect of routine mammography screening may increase women’s risk of developing radiation-induced breast cancer (11). The current recommendations for mammography screening have led women to start screening at a younger age and also to receive more frequent screening; this has amplified the amount of radiation to which the breasts are being exposed, and the effects are not trivial. In addition, women who are exposed to radiation for other purposes or women who are carriers of the BRCA (breast cancer susceptibility) gene are at an even higher risk of experiencing adverse effects from mammography radiation (12).

While not a direct reflection of the impact of mammography on breast cancer risk, other studies examining the effect of diagnostic chest x-rays on breast cancer risk have found that medical radiation exposure increases breast cancer risk (13).

Mammography can rupture tumors and spread malignant cells

Mammography involves compressing the breasts between two plates in order to spread out the breast tissue for imaging. Today’s mammogram equipment applies 42 pounds of pressure to the breasts. Not surprisingly, this can cause significant pain. However, there is also a serious health risk associated with the compression applied to the breasts. Only 22 pounds of pressure is needed to rupture the encapsulation of a cancerous tumor (14). The amount of pressure involved in a mammography procedure therefore has the potential to rupture existing tumors and spread malignant cells into the bloodstream (15).

Conflicts of interest and mammography recommendations

There is significant bias in the medical literature regarding mammography. This has led to significant breast cancer overdiagnosis and overtreatment, while also significantly influencing women’s perceptions about the purported effectiveness of mammography.

A literature review of 171 articles in the journal Evidence-Based Medicine found that a significant number of studies examining the effectiveness of mammography were published by interest groups and authors with vested interests in mammography screening. Scientific journal articles on breast cancer screening written by authors who have a vested interest in the practice of mammography tend to emphasize the potential benefits of mammography, while downplaying or outright rejecting the major harms such as overdiagnosis and overtreatment. Authors may have a vested interest in promoting mammography if they are receiving income from mammography screening programs or if they are contributing to scientific journals tied to political interest groups such as the American Cancer Society, which has financial ties with the makers of mammography equipment (16) (17).

Due to conflicts of interest, the research being used to develop recommendations for mammography screening protocols is biased and is not a true representation of the efficacy of mammography for reducing breast cancer mortality. This has had a large-scale impact on the development of mammography screening programs (18).

Perceptions of mammography benefits vs. reality

In a survey of U.S. women’s perceptions of mammography, 717 of 1,003 women (71.5 percent) said they believed that mammography reduced the risk of breast cancer deaths by at least half, and 723 women (72.1 percent) thought that at least 80 deaths would be prevented per 1,000 women who were invited for screening. However, based on U.S. mortality statistics, screening mammography prevents approximately one death per 1,000 women screened. Due to the influence of mammography propaganda, women’s perceptions of the effectiveness of mammography are overly optimistic and not even remotely a reflection of the true efficacy of mammography for preventing breast cancer deaths (19).

Research also shows that women who are better informed about the risk of overdetection and overdiagnosis of breast cancer associated with mammography screening are less likely to participate in mammography screening (20).

Informed choice is in jeopardy

Surveys indicate that women want to have balanced information and share the decision with their physician when it comes to whether or not they choose to go through screening mammography. However, many women have reported that they were never provided with information on the drawbacks of mammography, such as the risks of overdiagnosis, unnecessary cancer treatment, excessive radiation exposure, and potential for causing tumor rupture. The lack of balanced information about mammography provided for women jeopardizes their ability to make their own decisions regarding healthcare (21).

Making decisions regarding mammography

What is the best decision to make in regards to mammography? This is a question that many women are likely wondering as criticism of this diagnostic technique grows. The truth is that guidelines for the recommended frequency of mammography screening and the age at which screening should begin tend to vary from one organization or committee to another. The American Cancer Society states that women ages 40 to 44 should be given the choice to start annual breast cancer screening, women ages 45 to 54 should get mammograms every year, women 55 and older should switch to mammograms every two years, and screening should continue as long as a woman is in good health (22). The U.S. Preventive Services Task Force has more liberal recommendations and suggests that the decision to start mammography screening before 50 should be an “individual decision,” that women ages 50 to 74 years should receive mammograms every two years, and that there is insufficient evidence that women over 75 should even receive mammograms (23).

In light of all this information, it is important to emphasize that mammography screening is a highly personal decision that should be made with the assistance of an unbiased physician and with full knowledge of the potential drawbacks. Women should also be fully informed about alternative breast cancer screening tools. Some of these alternative tools may be helpful adjunct techniques to use with mammography, and others may actually be suitable replacements for mammography screening.

Alternative screening tools

Alternative screening tools to mammography include clinical breast exams, digital mammography, ultrasound, and thermography.

  • Clinical breast exam (CBE) is a physical exam of the breasts done by a trained healthcare provider. Addition of mammography screening to clinical breast exam did not reduce the risk of mortality from breast cancer, indicating that CBE is a highly effective screening tool (24). However, CBE is typically still combined with at least one additional type of screening tool, such as thermography or ultrasound.
  • Digital mammography allows for images of the breasts to be captured in a digital format rather than on film, as is done in traditional mammography. Studies show that digital mammography is at least as sensitive and specific, if not more sensitive and specific, than film mammography. In addition, digital mammography has advantages over film mammography in that the operator can access the images immediately, the images can be stored on computers, and the images can be enhanced and manipulated to allow for visualization of subtle changes in tissue structure in the breast (25). While digital mammography still involves compression of the breasts, it does use a lower dose of radiation than film mammography. Digital mammography may soon be the new stand-alone “gold standard” for breast cancer detection.
  • Thermography uses infrared technology to detect inflammatory patterns in breast tissue. It is noninvasive, does not emit radiation, can be done during pregnancy, and has the ability to effectively visualize dense breast tissue, unlike mammography. Thermography screening has demonstrated a high sensitivity and specificity. A high rate of false positives has been recognized as one of the drawbacks of this tool. However, these false positives may in fact be abnormal thermal patterns that are foretelling a future cancer that has not yet begun to grow to a physically detectable size. This theory is supported by studies in which thermography detected abnormal heat patterns in breasts several years before a breast cancer diagnosis was made. Thermography may therefore be a valuable screening tool due to its ability to detect functional changes in breast tissue before the onset of structural changes that occur in a cancerous state (26) (27) (28).
  • Ultrasound is a noninvasive diagnostic tool that does not emit radiation and is safe to use during pregnancy. Ultrasound has demonstrated the ability to detect breast cancer at rates comparable to mammography, while also being very economical and patient friendly. A potential drawback is that ultrasound may not be able to detect tumors less than 1 cm in size. In addition, ultrasound is a highly operator-dependent tool and requires the involvement of a skilled sonologist. Nonetheless, ultrasound is a very promising emerging tool for breast cancer screening and may one day be a viable stand-alone alternative to mammography (29).

Now I want to hear from you. Have you previously been informed about the drawbacks of mammography? Is mammography screening a part of your cancer prevention strategy? Have you tried alternative screening methods, and if so, what was your experience? Let us know in the comments below.

Never miss a post

Like what you're reading? Want to be notified of new content? Sign up for free.

  1. I have been doing thermograms for 4 yrs with good results on the tests. Recently a lump I’ve had for 17 yrs felt larger . Ultrasound showed something different. I now have lobular cancer. I will no longer use thermography. It doesn’t show cancer! Oh, I have also done ultrasound on lump for 5 yrs with no changes showing till Feb of this year.
    I stopped mammograms to avoid the radiation and now I have cancer. I hate mammograms but am afraid not to do them now.
    I’m the last person who should have cancer. I’ve been eating organic 7-8 yrs, avoid plastics, no gmos, no sodas, make own lotion, toothpaste, lip balm.
    How would u know a benign lump would turn into cancer? No heat showed on thermogram yet I have breast cancer!
    What is the answer?

    • I’m sorry to hear you have breast cancer. That must be intense.
      I would say another screening tool for increased breast cancer risk would be a urine estrogen metabolite test such as the DUTCH test, I think Chris has mentioned this test before in other blogs and shows.
      This test shows you how you are metabolizing your estrogens, which gives good insights into any breast or other reproductive cancer risk you have. This in conjunction with thermograms would be wonderful for screening. I also thing diagnostic mammography with any abnormal screening mammogram would be appropriate.

    • I am sorry to hear about your negative experience with thermography. As a midwife, I provide thermography screening as part of a comprehensive screening program. Unfortunately, there are many non-medical people offering thermography that do not have any training. People go to these places, usually because they are cheaper, and do not realize that they are putting themselves at risk. Also, thermography is one part of a screening. I have my patients to a thermogram along with an ultrasound as an initial screening. Neither mammograms, ultrasounds, nor thermography are meant to be stand-alone screening tools. When used in conjunction with each other, higher detection rates are found. It is also important to remember that no screening is 100%, and there are false positives and false negatives with every screening tool, as well as interval cancers. Also, it is important to inquire as to the type of thermography camera that is being used. I recommend an ICI or Flir system only. Good luck to you in your healing process.

  2. This is a very informative article, but it didn’t provided what I was looking for: in-depth auto-diagnosis information.
    It informed me the medical alternatives though.

    Thank you.

  3. I have been very happy with thermography after several years of stress from mammograms. Had too many because they thought something looked suspicious and then said no it is fine after making me repeat the mammograms too often.
    Thermography is unfortunately not covered by insurance and so not available to those who can not afford it.

  4. I’m 56 years old and up until about 5 years ago, I had routine mammograms every year. No doctor at any point ever advised me of any negative implications that could arise from the procedure itself nor was I ever advised of any negative consequences from exposure to radiation. Unfortunately, we women are often led like sheep to the slaughterhouse and never question the doctor, because, well, he/she knows best, right?

    • Kiama, you are spot on. It takes a level of courage and awareness to speak out for ourselves and ask questions when we’re in doubt.
      I’ve been a licensed X-ray tech and MRI tech for 20 yrs now. I’m fully aware of the dangers of x-rays, and I choose not to have mammograms at this point in my life; that may change depending on the benefits to risk ratio in the future.

      • 3D Breast imaging is done in breast MRI. I wish Chris would have talked about that in this article. Unfortunately, breast MRI is usually only done with a positive finding on a mammogram, and not as a screening tool by itself (its much too invasive and costly to be used as a screening tool).

  5. Please be sure to let your readers know that while there are reasons to question the risks vs. benefits of mammography for the general population, there is much more consensus that aggressive screening is absolutely worth the risk for women at elevated risk due to family history (on either paternal or maternal side) of multiple types of cancer, or to specific genetic alterations. These individuals may also be eligible for MRIs, which have fewer risks.

  6. I’ve been doing thermography for about 5 years. There is one spot that is warmer on my left breast than the corresponding spot on my right breast. The degree of variance goes up and down and does not seem to be influenced by interventions. We’ve tried all kinds of things. I do a lymph drainage massage daily. I use Lugol’s 2% iodine. I took breast health herbs. I even took Hoxsey formula for several months. No change. So I have stopped the breast health herbs and Hoxsey, and am continuing w iodine and lymph massage. What could be causing the inflammation? Still trying to identify. I have been eating GAPS for 4 years (bone broths, healthy fats, ferments, organ meats) – very clean organic diet – almost zero sugar. For the past several months I have been following a heavy metal detox protocol (from my naturopath & Louisa Williams) and just had an amalgam filling cleanly removed. Next thermagram, we’ll see if things are any different. I’m a boomer (67), raised on DDT, went through the fat is bad era. As healthy as I eat, I know I could still get cancer, but at least a thermagram finds the warm areas early, before anything has formed. For now, I am following it and hoping to find the cause of the hotter spot. A mammogram would not pick this up, so even though it’s frustrating trying to resolve this issue, I am glad to know of its existence.

  7. This type of article does not help women at all, only brings even more doubts and does not give a plausible solution. If you do not have a more effective solution, it’s best to be quiet.

  8. It really comes down to benefits vs. risks, doesn’t it?
    BTW – All mammograms are digital, unless you’re at some small clinic in the sticks. Film has been out of use in radiology departments for 10 yrs. And ultrasound will not be used by itself, only in conjunction with a mammogram; a radiologist will not read it out otherwise.
    This article is incomplete because it does not mention Breast MRI – which delivers the most detailed images. The current “standard of practice” is to do a mammo, then ultrasound, then MRI – in that order and as needed based on the results of the previous. It’s almost impossible to request only the MRI, because again, a radiologist will not agree to read it without the other relevant studies.

  9. Oh my, Chris. Have you waded into a hornet’s nest. You have done your usual thorough job at researching problems with mammography and restating these, but there could be a bit more balance and a few more solutions. As one of those “evil” physicians, as characterized above (who doesn’t herd her patients), I get dinged financially by my accountable care organization and insurance companies if I don’t refer patients per the current standard of care, or sued or have a patient with an agonizing death, if I miss a breast cancer. I do my best to help my patients make informed decisions as individuals. I wish to point out the following:
    1) Unfortunately, the evidence that thermography and ultrasound are adequate screening tools and save lives is wanting. Anecdotally, I have also seen patients like the unfortunate postee above, who relied on thermography. There is NO perfect screening tool, and all screening recommendations sacrifice the well being of the individual for the well being of “populations.” Fortunately, genetic research is bringing back interest in the care of the individual in determining who is at higher risk and what environmental and lifestyle factors turn cancer promoter and suppressor genes off and on. But progress has been slow to change the guidelines.
    2) Consider the toll on the woman who gets thermography and is told 10 years in advance of a treatable cancer that she has “a potentially pre-cancerous abnormality” on her thermogram (that mammography can’t “see” yet, and, pray tell, what am I do to with that information for this anxious patient?
    3) Cancers large enough to rupture on mammography screening should be detectable on exam. Incidentally, the USPHTF does not recommend self breast exam. This nihilistic recommendation is so typical of this entity. This would be a difficult thing to study, so they don’t have the info to recommend it. Why wouldn’t you check yourself? I have seen patients whose very large tumors were not seen on mammography OR US, and were discovered by the most low-tech method of all: palpation. What happens to women who wait until they have a palpable tumor is not pretty. So maybe they don’t die from their cancer, but just wish they had. Their treatment is more aggressive and will include chemotherapy and radiation, potentially leaving them with neuropathy, cognitive problems and other issues. The research bias for later treatment, is that maybe these women don’t die with metastatic breast cancer, but from heart disease caused by their radiation or some other more subtle effect of necessarily more aggressive treatment of a larger cancer. There are devastating financial consequences of going through “triple therapy,” even for women who have insurance. Mammography’s claim to fame is picking up smaller tumors (we are not talking about DCIS, which is a whole other can of worms). So, in these uncertain times, we are balancing false positive mammography and unnecessary biopsies, against these very real, unpleasant and potentially life-threatening issues for women with cancer diagnoses.
    4) Digital mammography is the standard of care, not an alternative screening tool at this point.
    5) Beware of 3D mammograms for routine screening — some protocols involve less radiation and some involve more, depending on the number of views, so ask, if it matters to you. Perhaps the solution is to get it once if you have dense breasts, and if normal, skip a year, per USPHSTF recs. They are typically more expensive because insurance companies are not yet covering.

    As a conscientious physician, who has breasts, this is what I do:
    I do my best to risk stratify my patients using a Gail model risk predictor (you can find the risk calculator on line, folks), and consider other lifestyle factors known to increase risk: weight, exercise, other signs of estrogen dominance, HRT use. If a patient is lower risk, we jointly consider going to the USPHSTF recs for starting later and checking every other year. I also advise my patients to lower their risk with lifestyle measures. Get those insulin levels down with weight loss, exercise and diet. A recent piece of research shows a 30% lower incidence of breast cancer recurrence in patients who fast 13 hours nightly (one of Chris’s faves). If you are estrogen dominant, AFTER you have done what you can with these lifestyle recs, consider adding a DIM (di-indole methane) supplement, with or without calcium glucarate.

    • Thank you Laurie for your thoughtful comment. I agree that this is a complicated and thorny issue, in part because as clinicians we don’t treat populations, we treat individuals.

      If a test leads to unnecessary and potentially risky treatment in nine people but saves one life, that would be viewed quite differently from the perspective of the person who’s life was saved and the nine people who underwent unnecessary treatment (though unfortunately they often never find out that it was unnecessary).

      Your case-by-case approach seems like a good strategy in a very murky area.


  10. I’m pleased to see this. I had a baseline mammograph at age 40, under pressure from my mother, and have stayed away every since. The small piece of data – that people who see doctors are sicker than those who don’t – helps me feel better. I rely on a homeopath and an energy healer for my health care – you will probably think I must be crazy or stupid for this, but at 68 I’m vigorous and doing farm work. Of course I also take care of my nutrition, live in clean air and spend a lot of time outdoors.

    I don’t have enough money to see a doctor or pay for Medicare Part B – I use that to pay for my good food and healthy lifestyle. So the mammogram issue has disappeared for me.

    And you know that the American Cancer Society is primarily funded by companies that make cancer equipment (and toxic chemicals – look it up).

  11. I have a feeling I am one of those who had a small tumor recognized as cancer and went through a very emotional roller coaster of a cancer diagnosis. I had 2 surgeries and then 33 rounds of radiation. I do feel they DO NOT inform you of the risks of mammograms! Not once has a physician explained that! I am really starting to advocate for myself! This makes me mad, sad, etc. that these mammograms are pushed so heavily and the conflicts! UGH!!! Everything seems profit driven not patient driven. I am so disappointed.

  12. Thank you for posting this article and the many comments above. I have a terrific OB-GYN who usually brings up the mammogram. Because I have extremely tiny breasts, I always ask her to give me a good reason why I really need to have one – I can feel my ribs very easily under my breasts. She can’t give me one so I always skip the annual mammogram. I’ve had two mammograms, both in my 40’s. I’m now 54. One was a baseline and one when I found a couple tiny (smaller than a lentil) lumps that turned out to be cysts per the ultrasound. About five months ago, I had a chest x-ray for an illness and a spot was found on my lung. I don’t smoke and I’m very health conscious so this puzzled and really concerned me. Instead of recommending a pulmonary specialist or wait and to see a few months (based on my research on lung cancer and lung spots), my primary care clinic kept insisting I have a mammogram. They were very angry with me for even questioning their judgement. I refused because this made no sense and there was nothing abnormal in my breasts. Shortly after, they decided my spot was calcium. I never got the mammogram. I have no idea why they and the radiologist would recommend mammography for a lung spot. Since I barely have any breast tissue, I’m really concerned about where the radiation would go with an unnecessary mammogram. Be an advocate for your health, research a lot and don’t just take your doctor’s word without doing your homework. Also, don’t be afraid to express your concerns with your doctor and ultimately make your own decision, get a second opinion or a new doctor. Decide not from fear or intimidation but from as much research and education from quality sources as you possibly can.

Leave a Reply