Friday, September 9, 2011

On Digital Infrared Thermal Imaging for Breast Cancer Detection

I recently got a letter published in the British Medical Journal on Digital Infrared Thermal Imaging for the detection of breast cancer. Since no copyright is taken out on these letters, I am reproducing it here:

On Digital Infrared Thermal Imaging for Breast Cancer Detection

Patricia Reed writes that digital infrared thermal imaging for breast cancer screening often receives very poor press and asks for feedback on the technology [1]. Including any breast cancer technology in a clinical trial is a very expensive endeavour. Part of the reason that digital infrared thermal imaging receives poor press in the media is because of the existence of studies that have demonstrated the technology to have sensitivities to the detection of breast cancer of just 18.6% [2] and 39% [3]. Furthermore, the technology as it is presently used takes a simple surface thermal image of a patient's breast. This provides thermal information from regions close to the skin surface, however, the technology is of questionable value when applied to small malignant lesions located far from the surface of the skin. In the future we will be able to make accurate in vivo temperature measurements in three dimensions across the patient's breast and at that point thermography may be shown to be an extremely powerful technology for the detection of breast cancer. However, three dimensional temperature measurements are more likely to be accomplished through technologies such as MR-thermography (based on using an MRI machine) as opposed to digital infrared thermal imaging. At present MR-thermography has technical limitations which restricts its potential use in the detection and characterization of breast cancer.

As for whether digital infrared thermal imaging based thermography can play a preventative role in screening by detecting abnormal vasculature is questionable. It is common for abnormal vasculature to grow after the formation of a malignant tumour in response to signaling factors released by the cancerous cells indicating their need for more nutrients. Thus detecting vascular abnormalities is likely to help in the detection of existing breast cancer. Preventing cancer by warning the patient of the existence of pre-cancerous tissues due to abnormal vasculature is much less likely.

Future breast cancer screening clinical trials are likely to have the burden of comparing any technique of interest with the results obtained by the combination of screening by both x-ray mammography and magnetic resonance imaging (MRI). Some of the earliest mortality data has recently started emerging on the use of these technologies for screening women at high risk for breast cancer. Studies have indicated very high survival rates among those patients with breast cancer 5 to 6 years after their original diagnosis [4-5].

Jacob Levman, PhD
Imaging Research
Sunnybrook Research Institute
University of Toronto

References

[1] Patricia Reed, "Re: Detection rates and mortality for evaluating breast cancer screening," British Medical Journal, (2010), E-Letter 340:c3106-v.

[2] Ernest Sterns, et al., "Thermography: Its relation to pathologic characteristics, vascularity, proliferation rate, and survival of patients with invasive ductal carcinoma of the breast," Cancer, (1996), 77(7):1324- 1328.

[3] Stephen Feig, et al., "Thermography, Mammography, and Clinical Examination in Breast Cancer Screening Review of 16,000 Studies," Radiology (1977), 122:123-127.

[4] Passaperuma K, Warner E, Hill KA, Narod SA, Balasingham S, Causer PA, Wong J, Jong RA, Verity L, Messner S, Eisen A, Ramsay E, Wright F, Yaffe MJ, Plewes DB, "Long-term results of the Toronto MRI breast surveillance study for women with BRCA1 or BRCA2 mutations," Annual meeting of the American Society of Clinical Oncology, Chicago, 2011.

[5] Rijnsburger, et al., "BRCA1-Associated Breast Cancers Present Differently From BRCA2-Associated and Familial Cases: Long-Term Follow-Up of the Dutch MRISC Screening Study," Journal of Clinical Oncology, (2010), 5265-5273.