Recently, I have had many questions from my patients regarding Breast Thermography or thermal breast imaging as an alternative to mammography for breast cancer screening in otherwise healthy women with no symptoms. So this article is long overdue! I must say that in researching this topic I have learnt so much myself. Thank you to all the patients who have asked me the questions and challenged me on this issue.
So what is THERMOGRAPHY and how is it used to detect breast cancer?
Thermal imaging uses a thermal (heat) sensitive digital infrared camera system to take an image of the infrared radiation (heat) being emitted by the skin. The image provided is made up of a range of colours with hotter areas appearing red and cooler areas appearing blue. It also notes and records temperature differentials or asymmetries between similar regions on either side of the body. Then, if abnormal heat patterns are detected as related to a specific region of interest or function, clinical correlation and further investigation can lead to diagnosis and treatment.
Thermal imaging is not a new technology. It was originally developed in the 1800’s. Over the years it has been improved upon and currently the main applications and uses are in the fields of security, the military and weather forecasting. Most of us have also seen it in action at airports where travellers with high fevers can be detected and are then isolated and tested for Avian or swine flu. It was only in 1982 that the FDA in the United States approved thermal imaging machines for use in the field of healthcare for animals and humans.
Its use in breast cancer detection is as follows: Cancerous cells will have a higher heat pattern because of the increased blood flow to the area as new blood vessels are formed in order to provide for the oxygen and nutrient demands of a growing cancer. Also, the metabolism of rapidly dividing cells, like the type found in cancer, is higher than normal cells. So the heat generated in this area would be more than the normal surrounding breast tissue.
Patients are required to undergo a baseline screen to see what their initial heat pattern is and then serial subsequent scans to detect any changes. Because temperature changes can be caused by many other factors, patients are required to take the following measures before such a test is performed: no make-up or deodorants; no excessive exercise for six hours before; no hot/cold drinks or food 30 minutes before; no excessive sun exposure within six hours; no sunburn at least a week before; wear loose clothing and try to be in a calm state.
Unlike mammography, there is no compression of the breast so women may find it more comfortable. In addition, thermal imaging does not expose the woman to any radiation, as occurs with mammography. Another important advantage would be that thermography is not less accurate in younger patients. The problem with mammography in patients under the age of 40, when breasts are more likely to be dense, is that diagnostic accuracy can be limited.
HEREIN LIES THE ATTRACTION OF THERMOGRAPHY.
Advocates of thermography are mainly advocating its use in younger woman, under 50, to detect early breast changes that could indicate a developing cancer.
At first glance then, it would appear that thermal imaging could well be an attractive alternative to mammography. Certainly the official websites would have us believe so. Thermography, however, has one major limitation: Breast MRI, mammography, and ultrasound (currently used tests) provide detailed anatomic information regarding position and size of a cancer. This information is essential to guide biopsy and excision. That’s something that thermography can’t do by itself.
In South Africa, there are many centres that offer thermography of the breast. The tests take 15 min to perform and results can take up to a week to be released, depending on the centre. The cost of the test varies from R600 to R800 per scan. Medical aids do not pay for the tests.
WHAT DOES THE MOST UP TO DATE MEDICAL RESEARCH SHOW?
As far back as 1977, a study involving some 16000 women showed that while mammograms detected 78% of breast cancers in the group studied, thermal imaging only detected 39%. So at this point, thermal imaging waned in popularity because it fell short.
Over the years that followed, technology improved and machines got better. So what happened? Results got better. In 2008, a smaller study showed promising benefit. This led to FDA approval for thermography but only in conjunction with mammography and not to replace mammography.
The medical fraternity though have not been entirely convinced: This is an extract from a published 2009 review entitled “emerging controversies in breast cancer imaging: is there a place for thermography?’’
“The biggest question concerns the efficacy of thermography to detect breast cancer. Despite various studies that suggest positive results for thermography, there has never been a major randomised controlled trial to determine baseline measurements of sensitivity and specificity. It is hard to imagine thermography being accepted by the conventional medical establishment without such data or evidence of cost effectiveness. In addition to questions about effectiveness of thermography, research needs to be conducted to determine the cost of using it for widespread cancer screening.”
Randomised controlled trials, as referred to in the above quote, are the types of studies that doctors regard as the best quality of research that helps us to develop policies to treat patients effectively. For Thermography, randomised controlled trials do not exist. Until new evidence is brought to light, mammography is still regarded as the “gold standard” for breast cancer screening.
The concept of breast thermography is based on a reasonable and scientifically plausible idea, namely that tumors produce more new blood vessels, which leads to more blood flow, which leads to more heat that can be detected and imaged. However, the way it is marketed and promoted as a replacement for mammography is of concern. There are many websites that promote it and make unsubstantiated claims about how effective it is, by itself, to detect breast cancer. These same websites also publish inaccurate information maligning mammography. Unfortunately, this contributes to the unsavory reputation the technique currently has in the medical community and continues to hinder its development in mainstream scientific medicine.