Why did Switzerland recommend abolishing mammography?

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Once upon a time, in a picturesque land of neutrality and luxury watches, a landmark medical article was drafted that would send far-reaching and long-lasting shock waves through the global medical community. The article would divide the country, and the world.

This historic moment is the 2014 article written by the Swiss Medical Board and published in the New England Journal of Medicine (one of the most respected medical journals in the world). The striking title reads “Abolishing mammography screening programs?”, and their report advocated for the abolition of systematic mammography screening. This sparked a scandal not only in Switzerland, but also in the international medical community, where Switzerland is regarded as a reputable and reliable scientific voice. The article, which received both ardent support and vehement backlash, has fuelled a continuing international debate over the role of mammography in systematic breast screening.

To recap the 2014 article that launched a thousand retorts:

In January 2013, the Swiss Medical Board, an independent health technology assessment initiative under the auspices of the Conference of Health Ministers of the Swiss Cantons, the Swiss Medical Association, and the Swiss Academy of Medical Sciences, was mandated to prepare a review on the utility of mammography screening.⁽¹⁾ 

After a year-long exhaustive examination of medical literature, they unveiled their findings.

In their report, the Swiss Medical Board declared that systematic mammography screening programmes for the early detection of breast cancer are no longer reasonable for women to attend. A systematic review of the existing literature allowed the Board to conclude that the effectiveness of mammography is still uncertain, over-diagnosis and false positive tests causeharm, and that the screening programmes have an unfavourable cost-effectiveness ratio.⁽²⁾

The board therefore recommended that no new systematic mammography screening programs be introduced and that a time limit be placed on existing programs.

Full Original Article available here.

What is the situation today, 12 years after this controversial publication in the New England Journal of Medicine?

To this day, Switzerland remains polarized, lacking a unified national consensus on the role of mammography in breast cancer screening. Only 12 out of the 26 cantons (states) of Switzerland propose systematic mammography screening.

The global medical community too, remains divided, mirroring the schism within Switzerland.

Is there no simple unifying answer?

Because health is both an individual condition and a mass population consideration, there are several nuances to consider. I will discuss those that are pertinent to the individual since my focus as a medical doctor is on the health and survival of my individual patients. I will not be accounting for cost-effectiveness and mass population considerations since my priority is not national budgets or political agendas.

1.     Age

In cantons using mammography for breast cancer screening,mammography is proposed every 2 years to women aged over 50. None of the cantons offer systematic mammography screening for women under the age of 50. This is medically justified as mammography is less effective at detecting cancer in premenopausal women with denser breasts since dense tissue can hide cancer cells. Furthermore, younger breast tissue is extremely sensitive and far more susceptible to damage from radiation. ⁽³⁾

However, there is debate on the international medical scene to advance the age of breast cancer screening because the largest increase in breast cancer incidence is occurring in younger women. In Switzerland, as in other countries, the largest increase in new breast cancer cases in 2023 occurred in women under 40.

So, mammography may be acceptable at detecting cancer in women after menopause, once breast tissue is less dense and less sensitive to radiation damage. But clearly an alternative is needed for younger women for whom mammography is not the most reliable nor safest screening technique.

2.     Potential harmful effects

Secondly, while many clinicians and patients have the impression that a mammogram is simply an innocuous test to detect breast cancer, the report of the Swiss Medical Board demonstrated that this screening may end up harming more women than it helps.⁽²⁾

The false-positive screening results and overdiagnosis of breast cancers flagged by the Swiss Medical Board are considered as harmful but inevitable consequences of mammography screening by the Swiss Cancer League. ⁽⁴⁾

There is also the harmful effect of mammography itself on the breast tissue. Mammography is an imaging technique that relies on ionizing radiation that can damage cells and DNA. The Swiss Cancer League acknowledges the risk of radiation-induced breast cancer.⁽⁴⁾ They estimate the risk of inducing breast cancer through radiation exposure during mammography at0.1%. While this a small percentage, it translates to many individual lives on a national and global scale. As the Swiss Cancer League states: “The risk is real, but minimal”. However, from an individual perspective, a real mammography-induced cancer is still a real cancer if you happen to be the unfortunate 0.1%.

It is evident that exposure to the ionizing radiation of mammography should be reduced as much as possible.

3.     Cancer detection

At the end of the day, the goal is to detect and treat cancer as early as possible. When diagnosed early, 99% of women with breast cancer survive. When diagnosed in the late stages of breast cancer, only 25% of women survive.⁽⁵⁾ The dramatic improvement in survival with earlier detection justifies that we do everything in our power to detect and treat breast cancer as early as possible. Not only does earlier detection decrease mortality, it also decreases the need for mastectomy and more invasive treatments. Evidence from medical reviews confirms that population-based breast cancer screening reduces breast cancer mortality in women over age 50, but also in ages 40-49. So clearly screening is beneficial, but the benefits of screening should largely outweigh its potential harms. And safe screening should also be available to younger women.

To this end, it is useful to be aware of the different screening tools available before we can compare them.

The oldest and most common screening tools are structural imaging techniques. These techniques allow us to see the structural elements of the body such as bones and soft tissues and tumours.

Mammography is the most common structural imaging technique for breast screening. It is cheap and easy to apply to a mass population. The breast is compressed between 2 sheets and bombarded with radiation. By measuring the absorption of this radiation, we get a picture of the tissues, or more precisely, of their layout and structure. We can see obvious structures like tumours, distortions, or calcifications. We cannot see blood flow or vessels,nor can we see inflammation.

MRI is the gold standard structural imaging technique for breasts, allowing us to see finer structures. This technique also shows us structural elements, but with more detail. The injection of contrast medium into the blood also allows us to visualise blood vessels and vascular formations. MRI is also the reference technique for evaluating the integrity of breast implants.  

Ultrasound is a technique that uses sound waves to create an image. It is widely available and non-invasive (albeit sometimes uncomfortable). However, it is also less precise than MRI and can be difficult to interpret in case of denser breast tissue.

The other options for imaging are functional imaging techniques.

Functional imaging analyses the function of tissues and organs, versus their structure. Older functional imaging techniques include PET scan and scintigraphy, which use radioactive tracers injected into the body to assess tissue and organ activity. They are most commonly used to detect and monitor cancer. Their obvious drawback is the introduction of radioactive substances into the body.

Thermology or Medical Thermography is a newer branch of functional imaging that relies on detecting infrared (heat) emissions from the body, allowing us to visualise tissue function without any radiation or invasive procedures. Thermology is also the technique that gives us the best chance at predicting and preventing breast cancer, as we will explore next.

4.     Cancer prevention

In an ideal world, we would detect cancer before it forms.We would identify breast tissue that is at risk for future cancer, allowing early preventive measures to be taken. And the potential future breast cancer would simply never develop.

Luckily, in medicine, this ideal world is already at our fingertips.

Cancer does not develop in a healthy breast. The breast tissue first becomes unhealthy. This is when functional tests that examine tissue function offer the unique benefit of identifying “at risk” breasts. Tissue function will exhibit anomalies before structural changes occur. In other words, the breast tissues are already functioning abnormally before the cancer or tumor forms.

Thermography is a non-invasive functional imaging technique that visualizes the function of the tissues. Like a PET scan or a scintigraphy, but without radiation. Thermography can detect cancers but offers the unique advantage of also detecting recognized cancer risk factors (such as fibrocystic or dense breast tissue, oestrogen dominance and inflammation),before cancer occurs.

This allows early preventive intervention and can guide lifestyle and health choices to thwart the progression to cancer.

A frequent example of this is postmenopausal hormone therapy: long-term hormone replacement therapy is a known risk factor for breast cancer. It can also increase breast density, making it harder for structural imaging techniques to detect cancer. This is when functional screening with thermography can allow primary prevention by detecting women with “at risk” breasts and knowing when to stop or reduce hormone replacement therapy.

A compromise?

Since the ultimate goal is protecting and promoting the health of the individual, my recommendations solely target the best outcomes for the individual. And will ignore national financial restrictions or political/cultural/industrial/religious or any other affiliations.

Thermography has yielded excellent results at detecting breast cancer in clinical trials, with some studies demonstrating a sensitivity of 97% (97% of cancers were detected).⁽⁶⁾ In a larger study in China in 2011, thermography was found to be more accurate for breast cancer screening than both ultrasound and mammography in small tumours (smaller than 2cm), with an accuracy of 97.1% and sensitivity of 90.4%.⁽⁷⁾

However, thermography is a functional exam and provides information different to structural imaging (MRI, ultrasound and mammogram). The information provided by structural and functional imaging is complimentary, not competitive. The 2 techniques do not replace each other but complement each other and bring different information to the table.

For optimum individual management, the best protocol is to use several tools and to combine thermography with structural imaging in order to achieve the most accurate and complete assessment.

Research also shows that the best results for detecting early breast cancer are obtained with a combination of structural and physiological imaging. In clinical studies, while mammography on its own has an 84% rate of cancer detection, combining mammography with thermography improved this to a 95% detection rate. ⁽⁸⁾ This can translate into potential survival for a patient whose cancer is detected in time. This improved performance remains true when combining thermography with the other structural imaging techniques (namely MRI and ultrasound).

Furthermore, thermography is the only imaging technique that gives us a shot at primary prevention (preventing cancer before it occurs), as opposed to catching cancer once it has already developed.

The true innocuity of thermography (no radiation, no contact, no invasive injections or contrast products, no compression) means there are absolutely no counter indications.

Thermography is a zero risk addition that can not only help detect breast cancer earlier, but can flag potential risk for future cancer and allow preventive intervention.

And to circle back to the topic of age: since thermography examines function and not structure, it is just as accurate in dense breast tissue. It remains reliable in younger women with denser breast tissue. This makes it the technique of choice for women under 50 with denser breasts that are harder to assess with mammography or ultrasound.

Additionally, the accuracy of thermography is not affected in patients with implants. Since there is no compression there is also zero risk of causing damage to the implants.

Final Thoughts

While Switzerland, and the world, remains divided and subject to considerations of national budgets and politics, doctors and patients still retain their right to individual freedom. Including their right to choose the best breast cancer screening protocols.

This is where the addition of thermography screening tostructural screening can make the difference with earlier breast cancer detection and breast cancer prediction.

And that can save a patient’s life.

 REFERENCES

1.    Biller-Andorno,Nikola; Jüni, Peter (2014). Abolishing mammography screening programs? A view from the Swiss Medical Board. New England Journal of Medicine,370(21):1965-1967. DOI: https://doi.org/10.1056/NEJMp1401875

2.    Vassilakos P, Catarino R, Boulvain M, Petignat P. Controversies in the mammography screening programme in Switzerland. Swiss Med Wkly. 2014 Apr 24;144:w13969. doi:10.4414/smw.2014.13969. PMID: 24764157.

3.    Pijpe A,Andrieu N, Easton D F, Kesminiene A, Cardis E, Noguès C et al. Exposure to diagnostic radiation and risk of breast cancer among carriers of BRCA1/2 mutations: retrospective cohort study (GENE-RAD-RISK) BMJ 2012; 345 :e5660doi:10.1136/bmj.e5660

4.    Doris Schopper, Chris de Wolf (2007). Breast cancer screening by mammography: International evidence and the situation in Switzerland. A joint publication of the Swiss Cancer League and Oncosuisse. Available online here.

5.    https://www.cancerresearchuk.org/about-cancer/breast-cancer/survival

6.    Parisky YR, SardiA, Hamm R, Hughes K, Esserman L, Rust S, Callahan K. Efficacy of computerized infrared imaging analysis to evaluate mammographically suspicious lesions. AJR Am J Roentgenol. 2003 Jan;180(1):263-9. doi: 10.2214/ajr.180.1.1800263. PMID:12490517.

7.    Yao X, Wei W, LiJ, Wang L, Xu Z, Wan Y, Li K, Sun S. A comparison of mammography,ultrasonography, and far-infrared thermography with pathological results in screening and early diagnosis of breast cancer. Asian Biomedicine. 2014 Feb 1;8(1):11-9. doi: https://doi.org/10.5372/1905-7415.0801.257

8.    Keyserlingk JR,Ahlgren PD, Yu E, Belliveau N. Infrared Imaging of the Breast: Initial Reappraisal Using High-Resolution Digital Technology in 100 Successive Cases of Stage I and II Breast Cancer. Breast J. 1998 Jul;4(4):245-51. doi:10.1046/j.1524-4741.1998.440245.x. PMID: 21223443.

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