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By Meg Sears, BASc, PhD and Magda Havas, BSc, PhD
Every day, 65 Canadian women are diagnosed with breast cancer and 14 die from it (1). You might think that early detection is a no-brainer, but Canadian researchers shook the cancer screening world with the strongest proof yet that for women aged 40 to 59, mammography is worse than useless.
A February 2014 report showed that after 25 years of follow-up there was no significant reduction in breast cancer deaths with routine mammography in women aged 40 to 59.(2) This is a large, strong study, on the heels of similar previous findings.
From 1980 to 1985, a total of 89,835 women in Nova Scotia, Quebec, Ontario, Manitoba, Alberta and British Columbia were randomly assigned to annual mammography or clinical screening by a health professional.
Mammography of women aged 40 to 59 years did not prevent deaths, and worse, it caused harm. Almost a quarter (22%) of supposedly invasive cancers diagnosed with mammography turned out to be false alarms, yet they entailed further tests and treatments (with associated risks and costs). Furthermore, in the mammography group, out of the 606 cancers that were treated researchers concluded that 106 would probably never have been a significant problem during the woman’s life. This “over-diagnosis” brings much distress and unnecessary costs.
This is the strongest evidence to date, although criticisms of routine mammography are not new. As well, the use of x-rays, a cancer-causing agent, to detect cancer should arguably be reserved for investigations where there is a clinical reason for concern, rather than in healthy individuals.(3) In addition, mammography may be painful and there is potential to harm sensitive tissues.
What is screening for?
So what are women to do, if they are younger than 60 years? “Watching out” for cancer is a compelling idea, and common sense argues for monitoring breast health. Note “health” rather than “disease.”
Presently, mammography and other screening detect established cancers. A highly suspicious screening showing a potentially cancerous lump leads to follow-up and the risks of anxiety, further tests and potential over-diagnosis.
Just think, what if there was a low cost, rapid, safe, readily accessible screening tool to catch the beginnings of a cancerous processes, before a cancer is established? Some Canadian physicians screen for breast health to halt and even reverse a precancerous process before it becomes established. Inconclusive or weak findings could be followed with repeated screening before invasive testing. In the meantime people could be supported in reducing their cancer exposures, through changes to the products they ingest or use, exercise, stress management and improvements to their life situations. (Did you know that income is a much stronger predictor of ill health than behaviour?).
That said, knowledge can encourage changes. Screening of lung abnormalities spur on smoking cessation.(4) Women concerned with breast cancer deserve information as well.
Of course, strong or repeated indications of potential problems would trigger further conventional investigations. Follow-up with ultrasound avoids exposure to x-rays, and the pain and risks of compression of a tumour. The flip side is that if screening for some reason doesn’t detect a cancer then a false sense of security may delay diagnosis.
Thermography – a low cost test for pre-emptive detection?
Thermography, recently evolved as digitally-enhanced infrared thermal imagery (DITI), is a painless, non-invasive, non-contact technology that is fast, radiation-free and comparatively inexpensive. A camera detects the temperature of the surface of the skin, and a computer program is used to produce and score images. DITI measures changes in physiology (metabolism) rather than structural changes seen with mammography, CT scan, ultrasound and MRI.
Thermography may be used for many conditions, since higher temperatures are associated with inflammatory conditions, such as cancer, infection or arthritis. It is commonly applied to breast screening. Tumors are warmer than surrounding tissue, as they are growing rapidly and have an increased blood supply. Hotter regions of skin may indicate underlying malignancies, infections or pre-cancerous inflammation, while benign cysts are cooler (thermography can differentiate these conditions, that appear similar in mammograms). In degenerative conditions, thermography can also be used to detect cooler areas with restricted blood flow.
Thermography could particularly benefit:
Does this sound too good to be true? Unfortunately, for now, in Canada, it is. Thermography has suffered from a lack of standardization and regulation, along with easy accessibility. A diagnostic radiologist (who would read mammogram results) has had years of training, but anyone can purchase a thermal imaging camera, take photographs of breasts and see differences in temperature between the two. Ultimately, the test is only as good as the patient preparation; the skills of the technician who takes the photographs; and the expertise of the doctor who interprets the images in the context of the individual patient, and provides personal advice and follow-up. (The same applies to all imaging – MRI, ultrasound, mammography and thermography.)
The large scale research that backs other screening techniques has not been replicated for breast screening with thermography, prompting Health Canada to issue an alert in 2012, stating that thermal imaging was not approved for screening for breast cancer, warning “it may present a potential risk to women relying on the results.”
One form of thermography has been approved by Health Canada as an supplementary diagnostic tool. The AlfaSight 9000 detects the temperature of over 100 points on the human body, including areas around the breast, before and after a cold challenge. Areas which are not symmetrical in the breast region, or that appear warmer after the cold challenge, may merit more careful examination. This technique can be used to evaluate health throughout the body.
Thermography has remarkable potential as an early indicator of problems, particularly for tumours or their enhanced blood supply near the surface of the skin. In a study published in 1980, using less sophisticated equipment but rigorous methods, Gautherie and Gros reported on examinations of 58,000 patients. More than a third of 1,245 patients with “suspicious but not conclusive” thermal images (Th III, on a scale from I to V) developed histologically confirmed cancer within 5 years of followup.(5) Investigators also used fine wires to measure heat production in tumours in patients forgoing treatment, and found that breast cancers that grew more rapidly (had the shortest doubling time) produced the most heat (the rate of metabolism was higher) (Figure 2).
In competent hands, thermography can be very effective. In a 2008 study,(6) out of 94 patients with biopsies, DITI identified 58 out of 60 malignancies, with 97% sensitivity, 44% specificity, and 82% negative predictive value. These numbers are more favourable than reported for mammography plus ultrasound, and are comparable to data for MRI, in a 5-year surveillance study.(7)
The future of thermography
In 2012, Health Canada indicated in a letter to the College of Family Physicians of Canada that thermography was not authorized for breast cancer screening.(8) This was based on a lack of research.
Mammography poses a finite cancer risk and is now established as inappropriate for women younger than 60 years. With women’s strong desire to know about breast health and for early detection of breast cancer we ask, “Can thermography help to fill that gap?”
In healthy individuals, routine thermography to detect metabolic abnormalities (rather than mammography to see structural changes) may provide helpful preliminary information both to support daily choices, as well as results that may merit further investigation. Thermography can be offered to all ages, and compliance may well be higher because:
Instead of restricting thermography for breast health, Health Canada and the Canadian Institutes for Health Research should be promoting screening and related research. We need guidelines on the proper use of, and qualified diagnosis of breast abnormalities with thermography, beyond AlfaSight 9000.
It is time to validate and “fine tune” thermography and appropriate follow-up responses, for not only early detection but also true prevention.
Meg Sears, PhD is a Board Member of Prevent Cancer Now. Magda Havas, PhD is an Associate Professor at Trent University, Peterborough, ON, Canada (www.magdahavas.com).