Thermography: Is it a Reliable Alternative to Mammograms?

A mammogram (L) is an X-ray image of the breast that can identify tissue types with different densities, such as masses within the breast. Thermography (R) produces an infrared image that shows the patterns of heat on or near the surface of the body. Image source: U.S. Food and Drug Administration

In discussions about mammography or breast screenings, you may have heard the word “thermography” suggested as an alternative to mammograms. But what is thermography? Is it a good alternative for those who find mammograms uncomfortable or painful or are concerned about radiation exposure? Short answer: while mammography isn’t perfect, it remains the best screening tool for breast cancer in the United States. We’ll dive into the science of thermography and mammograms so that you have the information you need to talk to your doctor about what breast screening options are right for you.

What is Thermography?

Thermography uses an infrared camera to detect areas in the breast that are generating a lot of heat. Think about those spy movies and tv shows where the hero uses special glasses and sees the rainbow-colored shapes of the bad guys on the other side of the wall. Here’s the theory behind why it works to detect cancer: growing a tumor takes a lot of energy, so the cancer cells will “trick” the body into sending more blood to the tumor site. That extra blood flow and cellular activity will show up red on an infrared camera, showing excess heat in that area of the breast.

How is Thermography Different from a Mammogram?

There are two big differences between these two screening modalities that seem to be of interest to patients. The thermography machine uses touchless technology, so there is no pressure or squeezing of the breast. And thermography uses infrared light to show heat, rather than the very small amount of radiation of a mammogram to show shapes and opacity of those shapes inside the breast tissue. Some lesser-known potential benefits are that dense breast tissue poses less of an obstacle for thermography compared to mammography, and it is a cheaper test. 

Here’s the main difference that is concerning to doctors who deal with cancer: thermography cannot yet detect cancer that is at the local stage, only large tumors. Thermography also cannot assess potentially cancerous activity in nearby lymph nodes like mammograms can. 

Peer-reviewed articles on thermography were reviewed for this blog, some sourced from a thermography imaging provider’s website. One article focused on the benefit of thermography in India, a country with fewer healthcare resources, where, yes, a thermography screening is better than no screening for breast cancer. In a study conducted in the United States, participants for the study were identified because they had already had a mammogram and were recommended to follow up with a biopsy. For this study, some important science terms are highlighted: sensitivity and specificity. Any medical test or tool is evaluated on its sensitivity and specificity scores. The sensitivity of a test measures how often the test finds a positive result when the patient is sick, or in this case, finds breast cancer when the patient actually has breast cancer. The specificity of a test measures how often a test finds a negative result when the patient is actually healthy or determines the patient doesn’t have breast cancer and they actually don’t. 

In this study and others, thermography was found to be highly sensitive but had very poor specificity. For this study, that meant that thermography falsely indicated breast cancer in 56% of the patients who didn’t actually have breast cancer. That is worse than a coin toss. This means that patients who would receive thermography as an initial screening would have a much higher rate of false positives than those who receive screening mammograms. With the current thermography technology, this would actually mean more follow-up testing than we currently experience with mammograms, which is already considered too high of a false-positive rate.

Bottom line

While there is room to improve mammogram technology or come up with a better screening tool, current thermography technology is not it. Thermography is a great technology to continue to study and improve and to use in areas where mammography is inaccessible due to cost, but is not generally beneficial as a screening tool for the average woman in the US. Even in the peer-reviewed journal articles read for this blog that were positive of thermography, none suggested thermography as a replacement for mammography. In the United States, mammography is more widely available than thermography, is a more precise technology, and screening mammograms are covered at no cost by insurance companies if the patient is over 40.

 

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