Thermography: Worse than useless

Earlier this spring, I described the Choosing Wisely campaign in the United States, an initiative designed to redirect resources away from medical treatments that are useless or harmful. In the spirit of the campaign, I suggested Five Things Pharmacists and Patients Should Question. My list included unvalidated IgG food intolerance blood tests like Hemocode, dubious “Body Chemistry Balancing”, inaccurate heel ultrasound bone density testing, and saliva hormone testing. I also singled out breast thermography as a particularly questionable test that pharmacies offer. Cancer tumours need a rich blood flow to grow, so cancer cells secrete chemicals to stimulate the development of new blood vessels. More blood flow means warmer tissue. Thermography, sometimes called digital infrared thermal imaging (DITI) uses infrared measurement to detect skin temperature differences. Thermography has emerged as an alternative therapy offered by naturopaths, homeopaths, and some health professionals, like pharmacists. Note the claims made:

• Finlandia Pharmacy in Vancouver says thermography “can detect the first signs of cancer formation before any other diagnostic service currently in use”
• Wisdom Thermography, offering services at Marks Pharmacy in Vancouver, claims with thermography, “abnormal heat signatures can be detected up to 10 years prior to tumour development”. They even add,
  

  So, if the recent Canadian Task Force on Preventative Health Recommendation has you feeling like your options are limited, then take Thermography into consideration as additional way to get an idea of what is going on in your body. Thermography has been found to be 90% accurate and, simply put, by adding this screening to breast exams and Mammograms the chances of early detection and survival are increased.

•  Avita Integrative Health and pharmacy in Brampton claims, “thermography of the human breast can make a profound and positive impact on breast cancer and other breast disease.”

Perhaps not surprisingly none provide supporting evidence for these statements. That’s because the scientific evidence actually shows thermography isn’t a useful tool for screening or diagnosis. This evidence review on thermography [PDF] from the Canadian Agency for Drugs and Technologies in Health is a excellent summary from an unbiased, non-partisan source. The analysis, based on a comprehensive review of the evidence, notes that thermography is worse than mammography in terms of sensitivity, specificity, and predictive value. That is, it gives more false positives, leading to unnecessary worry and investigations, yet it misses actual cancer. The bottom line is that there is no persuasive evidence to show thermography has any value for screening or detecting cancer, either used on its own or in combination with mammography.

In light of the lack of evidence, Health Canada does not licence thermography in Canada, nor does it recommend its use as a screening technique. It notes,

“Claims that thermography is useful in diagnosing breast cancer have not been proven, and thermography equipment has not been licensed for breast cancer screening in Canada.”

CBC took thermography on this week, running several features on the practice, including this clip on The National, where this naturopath clinic is featured which claims thermography offers a “early detection program” for cancer. In response to CBC’s coverage of thermography, two provinces (to date) have already issued “cease and desist” letters to clinics offering thermography. Interviews with physicians identify that thermography is driving women to seek investigations when none are necessary:

Test is ‘actually useless’

Medical experts take issue with claims trumpeting the benefits of thermography in diagnosing breast disease. Nancy Wadden, a St. John’s doctor who chairs the mammography accreditation program of the Canadian Association of Radiologists, says women are paying big money for a test that is “actually useless.”  Wadden says that women who actually need treatment face longer wait times because of women who register false positives after thermography. “These women have a significant number of false positives, so then they are coming and they are clogging up my ultrasound list and my mammogram list and then displacing the people who really need to have the test, who are waiting there,” Wadden said. “Their length of time to get a diagnosis is prolonged, because we’ve got people who have had this useless test that has given a false positive result.”

Worse than useless. Harmful.

And just today, Health Canada has taken further action, issuing another advisory:

“Health Canada is not aware of any clinical evidence that thermography can be used effectively as a screening technique for the early detection of breast cancer” “As such, it may present a potential risk to women relying on the results.”

There is justified debate on the utility of mammograms for breast cancer screening. In particular, overscreening those at low risk of breast cancer appears to be harming more than it benefits. (This is not new, and has been a discussion point for several years here over at Science-Based Medicine where I also blog. David Gorski’s post this week gives a good summary of the controversy and the evidence.) Clearly driven by this vigorous debate on the merits of mammograms, thermography has emerged as an “alternative” treatment that is arguably worse than mammography by every measure.

Kudos to the CBC for their activism on thermography. Despite the lack of any credible evidence, and supported by a large network of naturopaths, homeopaths and even some pharmacists, thermography is widely available in Canada.  The bottom line with thermography is that it hurts and harms more than it helps. Regrettably, it seems that some pharmacies and other providers are either ignorant of the scientific evidence, or are simply indifferent to it.