Mammograms Do Not Find All Breast Cancers - Dr. Axe

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Mammograms Do Not Find All Breast Cancers


Mammograms - Dr. Axe

Breast cancer now affects about 1 in 8 U.S. women at some point during the course of their lifetime. It is the second most common cancer among women (after skin cancer) and the second leading cancer-related cause of death.

The National Cancer Institute (NCI) estimates that as of 2018, approximately 260,000 new cases of invasive breast cancer are diagnosed each year in the U.S. alone. (1) Although survival rates for breast cancer have gone up in recent decades, screening options remain a very controversial issue.

Clinical trials regarding breast cancer screening technologies, including mammograms, have overall shown conflicting results. More than 85 percent of U.S. women aged 40 years or older have had at least one screening mammogram in their lifetime. (2) Today, not all experts agree on which screening procedures should be recommended to the public, especially in younger women who are under the age of 50.

In March 2019, for the first time in more than 20 years, the U.S. Food and Drug Administration (FDA) proposed amendments to key regulations regarding the quality and safety of mammography services. The FDA has now admitted that while mammography may be the best screening test to search for breast cancer, it does not find all breast cancer — especially in patients with high breast tissue density, which makes it harder to find breast cancer on a mammogram.

Mammograms are now known to be less reliable in women with dense breasts, which is estimated to be more than half of all women over the age of 40. Because of this, going forward healthcare providers will need to give women more information about risks associated with dense breasts and other factors that can make it more difficult to accurately screen for breast cancer.


The Standard Mammogram Recommendations

Mammograms are performed today for two reasons: They help detect breast cancer and also help confirm a diagnosis if another screening option shows the presence of cancerous cells. Mammograms might be able to help screen for breast cancer in some cases, but they do nothing to help prevent or treat breast cancer (in fact, the opposite might be true).

Whether or not to be screened for breast cancer by undergoing a yearly (or bi-yearly) mammography can be a very confusing and difficult choice. There are dozens of different opinions available today regarding how often to be screened, starting at what age, and what the potential risks of various screening options might be. To help you make an informed decision, it’s important to understand the benefits, limitations and risks of all your screening options.

The United States Preventive Services Task Force (USPSTF) released a revised recommendation in 2009 stating that women in their 40s should NOT necessarily have yearly mammograms, and need to carefully the weigh the risks considering their personal situation. This recommendation conflicts with those of the American Cancer Society (ACS) and other authoritative groups, leaving women unsure of what to do in order to help protect themselves from cancer.

The American College of Physicians has also made recommendations similar to the USPSTF, and the National Breast Cancer Coalition has routinely warned women of the limitations and potential for harm that mammograms hold.

Current Breast Cancer Screening Recommendations:

Below is the current summary of mammography recommendations released by the U.S. Preventative Services Task Force as of 2009: (3)

  • Women, Ages 50–74 Years: biennial screening (every two years) mammography is recommended. The USPSTF states “there is high certainty that the net benefit is moderate, or there is moderate certainty that the net benefit is moderate to substantial.”
  • Women, Before the Age of 50 Years: The USPSTF states “The decision to start regular, biennial screening mammography before the age of 50 years should be an individual one and take patient context into account, including the patient’s values regarding specific benefits and harms.”

According to women’s health expert Dr. Christine Northrup, The United States Preventive Services Task Force is a trustworthy, influential government-appointed group that offers non-bias guidance to doctors, insurance companies and policymakers. They revised their guidelines in 2009 after reviewing all of the available evidence, and changed their recommendations regarding mammograms as to advise women to start regular breast cancer screening at age 50 (every two years) instead of at age 40. (4)

Although other screening options exist, and mammograms won’t help treat cancer even in women over 50, the USPSTF feels they can be beneficial for detecting cancer in women at a high risk.

On the other hand, the American Cancer Society offers these recommendations regarding breast cancer screening: (5)

  • Women ages 40 to 44: should have the choice to start annual breast cancer screening with mammograms if they wish to do so. The risks of screening as well as the potential benefits should be considered.
  • Women age 45 to 54: should get mammograms every year.
  • Women age 55 and older: should switch to mammograms every two years or have the choice to continue yearly screening.

The guidelines above are meant for women at average risk for breast cancer. Women with a personal history of breast cancer, a family history of breast cancer, a genetic mutation known to increase risk of breast cancer (such as BRCA), and women who had radiation therapy to the chest before the age of 30 are known to have an even higher risk for breast cancer.

Although The American Cancer Society does support mammograms because they can sometimes help detect cancer in its early stages, such as ductal carcinoma in situ or DCIS, they also point out that “mammograms are not perfect.” They state on their website that “mammograms miss some cancers. And sometimes more tests will be needed to find out if something found on a mammogram is or is not cancer. There’s also a small possibility of being diagnosed with a cancer that never would have caused any problems had it not been found during screening.”

History of Mammogram Research

One reason that mammograms remain controversial is that much of the research done to determine their pros and cons was carried out decades ago, when the quality of imaging devices was much poorer. Clinical trials to determine if mammograms are beneficial and safe were first conducted in the 1970s, and since this time these trials have been criticized for having many flaws and limitations.

The U.S., Sweden, Canada and the U.K. all conducted trials in the ’70s that showed women had a better chance of detecting breast cancer in its early stages if they were screened using mammograms while also receiving usual medical care, compared to women who were not being screened with mammograms but still receiving usual medical care.

Because of this finding, it was determined that it was unethical to purposefully withhold mammogram screenings from certain women going forward for the sake of research. That meant that well-controlled, randomized, blinded trials comparing mammograms to no mammograms were mostly discontinued after the ’70s, making it hard to draw definitive conclusions.

Since this time other studies have found that mammography tends to be less accurate in women under the age of 50. Two reasons why mammograms are now recommended for women over 50 (but often not for those who are younger) is that there are fewer breast cancer cases in younger women to begin with, and secondly that younger women have denser breast tissue that makes mammograms less accurate.

Mammograms are most accurate in post-menopausal women who have more fatty breast tissue, but less so in younger women. Research has revealed that the benefits of mammography are mostly limited to women between the ages of 55 and 69, but that “no statistically significant benefits are seen outside this age range.” (6)


The facts above about the inaccuracy of mammograms in younger women, coupled with recent findings that mammograms can pose certain risks, have led some health authorities to change their minds about whether women should receive mammograms. New findings are constantly being released, and opinions often change — but as you’ll learn, there are very real risks for undergoing yearly mammograms and following up “false positives” with risky conventional treatments.

Potential Dangers of Mammograms

In 2001, the Cochrane Institute carried out an analysis to study findings about mammography screening and pointed out that overall screening can actually be harmful because it frequently leads to overdiagnosis and overtreatment. They also found that many advocacy groups and websites in favor of mammograms accepted sponsorship from the mammogram industry without restriction. This results in certain organizations promoting the benefits of mammograms without also revealing the risks and drawbacks. (7) This is same issue is also a problem when it comes to treating cancer naturally versus with more aggressive approaches.

How and why mammograms can increase cancer risk:

1. Overdiagnosing and Overtreating

Ductal carcinoma in situ (DCIS) is a type of cancerous cell present in 10 percent of all women, and in 15–60 percent of women in their 40s. DCIS means that abnormal cells have been found in the lining of the breast milk duct, but that they have not spread outside of the ducts into the surrounding breast tissue. DCIS itself is not life-threatening, but having DCIS can increase the risk of developing an invasive breast cancer later on.

So although detection of DCIS cells can be dangerous in some women, this isn’t always the case. As Dr. Michael Cohen of Sloan-Kettering Hospital says, “It may stay there a women’s whole life and never invade surrounding tissue … we don’t know how to tell the one that won’t spread from one that will.”

This creates a big problem for doctors, because if a mammogram picks up DCIS cells in a woman’s breast, there’s no way to know how to respond with and manage their condition appropriately. A host of invasive and dangerous steps might be taken as part of a treatment plan for cancer in response to DCIS cell abnormalities, even before they ever even have the chance to progress. Oftentimes the recommendation after DCIS is detected is for the patient to start treatment with surgery, radiation, hormone therapy or chemotherapy to stop cancer from progressing.

Since mammography screening was first introduced in the 1970s, DCIS detection has increased dramatically. The National Cancer Institute (NCI) reported the incidence of DCIS in 2004 to be 32.5 per 100,000 women. This is considerably higher than the 5.8 per 100,000 was that estimated in 1975. (8) Some speculate that radiation and pressure to which women are subjected to during mammograms is responsible for a high percentage of the increase in DCIS, but even if it isn’t, there’s a real concern for overtreating DCIS and causing negative side effects.

2. Increases Radiation Exposure

Mammograms expose your body to very high levels of radiation — some even speculate radiation that is 1,000 times greater than a chest x-ray. (9) It’s been theorized that ionizing radiation mutates cells, and the mechanical pressure can spread cells that are already malignant (as can biopsies).

Aside from mammograms not being very accurate in younger women, another potential danger is that the breast tissue of women under 40 (pre-menopausal women) is highly sensitive to radiation. The Breast Cancer Organization points out that “diagnostic radiation from mammography in women under 40, or possibly in women before menopause in general, may well carry an increased risk of cancer associated with radiation alone.” They also state that radiation is very dangerous for pregnant women − even more so than chemotherapy!

Breast cancer risk increases by 1 percent for every additional unit of radiation. The Department of Epidemiology and Radiology at University Medical Center Groningen in the Netherlands has found that among all high-risk women, average increased risk of breast cancer due to low-dose radiation exposure was 1.5 times greater than that of high-risk women not exposed to low-dose radiation. High-risk women exposed before age 20, or with five or more exposures, were 2.5 times more likely to develop breast cancer than high-risk women not exposed to low-dose radiation!

Research published by Harvard Medical School also states that for every 1 gray of radiation (a unit that measures the absorbed radiation dose), a woman’s risk for heart disease rises by 7.4 percent. (10)

3. Causes Increased Stress and Anxiety

Most people aren’t aware that all of us have cancerous cells in our body to some degree, but our immune system is able to fight them very effectively, provided we don’t have nutrient deficiencies or toxicity of some sort in our bodies. We are led to believe that cancerous or mutates cells are completely abnormal and alarming, but this is not in fact the case. As you’ve seen above, overreacting and overtreating detected cancerous cells can do more harm than good in some cases.

One thing that might surprise you about cancer: Our stress levels and beliefs about our own health can impact if we actually become sick or stay healthy. Clinical studies done over the past 30 years have provided strong evidence for links between “chronic stress, depression and social isolation and cancer progression.” (11) It’s speculated that the high amount of undue stress that occurs when a person believes that they have cancer can cause them to succumb to a lack of hope and further illness.

High amounts of anxiety, stress, and a lack of hope is not something to take lightly − studies have found that for some people optimism and a positive outlook might actually increase health and chance of achieving recovery. (12) Dr. Joseph Mercola agrees. He states that, “Just thinking you may have breast cancer, when you really do not, focuses your mind on fear and disease, and is actually enough to trigger an illness in your body. So a false positive on a mammogram, or an unnecessary biopsy, can really be damaging.” (12)

The FDA’s Stance on Accuracy of Mammograms:

According to a March 2019 statement released by the FDA, “As part of our overall commitment to protecting the health of women, we’re proposing new policies to modernize our oversight of mammography services, by capitalizing on a number of important advances in mammography, like the increased use of 3-D digital screening tools and the need for more uniform breast density reporting….Today’s proposed rule would help to ensure patients continue to benefit from advances in new tools and robust oversight of this field.”

The FDA’s 2019 proposed amendments are intended to:

  • Improve communication and medical decision making between patients and their doctors. New language in mammogram reports will help ensure patients have access to information about the impact that risk factors like breast density and others have when it comes to developing breast cancer.
  • Provide patients and their healthcare providers with more information about breast density. “Dense breasts” are considered breasts with a higher proportion of fibroglandular tissue compared to fatty tissue. Dense breasts have been identified as a risk factor for developing breast cancer. It’s estimated that more than half of women over the age of 40 in the U.S. have dense breasts.
  • Better explain how breast density can influence the accuracy of mammography services. Dense breasts can obscure signs of breast cancer and lower the sensitivity of mammogram images. Dense breast tissue makes it harder for doctors to see signs of cancer, which means mammograms can be less accurate. The goal is for patients with dense breasts to better understand their personal risk and to speak with their health care provider about screening and treatment options based on their individual situation.
  • Health care professionals will also now be provided information about three additional categories regarding breast cancer risk, including “known biopsy proven malignancy.”
  • Additionally, new regulations will likely be established for mammography facilities regarding the information they share they patients. Facilities will need to notify patients if testing does not meet the FDA’s quality standards, this way patients (such as those with high breast density) will know if they should seek out other imaging tests in addition to mammograms.

Facts About Mammography Risks

  • Mammography screenings induce a lot of unnecessary procedures, anxiety and costs. A large-scale Swedish study found that 726 women of 60,000 who underwent mammograms were referred to oncologists for treatment. But roughly 70 percent of those women were actually cancer-free! (13) The proportion of false positive results was particularly high in women under 50 years old. A whopping 86 percent of the women under 50 who were referred for further treatment wound up being found to be cancer-free.
  • Another analyses done by the Nordic Cochrane Center involving 800,000 women found no statistically significant reduction in breast cancer mortality in the first nine years of a mammogram screening program. (14)
  • The Lancet reports that mammograms are very inaccurate in younger women. (15) Of the 5 percent of referrals to oncologists after mammograms are performed, studies show that between 20–93 percent of cases are believed to be “false positives.” How could the number of inaccurate diagnoses be so high? The belief is that in a very high percentage of those who receive false positive diagnoses, the inaccurate diagnoses is made due to unclear readings as a result of high breast density.
  • Another study, conducted by members of the Radiological Society of North America found that a woman who has yearly mammograms between ages 40 and 49 has about a 30 percent chance of having a false-positive mammogram at some point in that decade. (16) Research also shows that a whopping 62 percent of women don’t even want to take false-positive results into account when deciding about screening options.
  • A Canadian study spanning 13 years involving 39,405 women concluded that mammography screening does not result in a decrease in the absolute rate of advanced breast cancer and does not reduce mortality when compared to physical examination only. The researchers concluded that women aged 50–59 years consider the option of an annual physical examination plus regular self-examination as an alternative to annual mammograms. (17)

A Better Option Over Mammography

Thermography is a new, non-invasive technology that does not use radiation or compression to screen for breast cancer. Breast density also does not affect its results, meaning it’s accurate in younger women, too. It’s painless, easy to perform, can be performed in pregnant women, lower in cost than mammograms and can be just as effective and accurate (if not more). (18)

Thermography measures infrared heat from your body and interprets the information in images that can tracked over time to look for changes. Using thermography, doctors can detect cancerous tumors in its early stages, offering patients the best chance of recovery.

Of course, prevention is also key. Eat a healthy diet with cancer-fighting foods, get enough exercise, reduce stress and limit toxin exposure to lower your risk as much as possible.

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