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Friday, January 1, 2010

Thermography for Breast Cancer Detection

The use of body temperature to diagnose disease dates back to 480 B.C. when Hippocrates wrote about spreading mud on his patients, suspecting the areas that dried first might indicate possible problems in underlying organs. Since then, technological progress has made thermography, a modern technique for measuring body temperature, possible.

Thermography has been studied for its usefulness in breast cancer detection since 1956 and the United States Food and Drug Administration approved it as an adjunctive screening tool in 1982. The popularity of screening mammography caused thermography to fall out of favor, but recent revelations about the limitations and adverse effects of mammograms has renewed interested in this promising alternative.

The Difference

While mammograms measure anatomy, thermograms measure physiology. Mammography uses compression and ionizing radiation to take pictures of breast tissue, making the procedure painful and increasing the risk of developing cancer. Thermography is a painless test that uses infrared imaging to detect heat patterns on the surface of the skin related to inflammation, blood flow and angiogenesis, the formation of new blood vessels. Angiogenesis is a critical step in the growth of cancer because as abnormal cells increase in number, so do their requirements for oxygen and nutrients, the food needed to fuel proliferation. To meet their expanding needs, tumors generate new vessels to increase blood flow, and this in turn increases skin temperature.

Earlier Detection

Because inflammatory and vascular changes related to cancer growth can be detected sooner than solid tumors, which may take years to grow large enough to block x-ray beams and be identified on mammograms, thermograms can identify signs of malignancy in its earliest stages. Some experts estimate that thermography recognizes cancerous or pre-cancerous changes up to ten years earlier than any other procedure, mammography included.

Because earlier detection can lead to earlier treatment and improved prognosis, thermograms offer significant survival benefits. A study published in the American Journal of Obstetrics and Gynecology followed almost 500 women diagnosed with breast cancer for five years. Only one of the two groups was screened with thermography. For these women, thermograms tested positive (abnormal), finding malignant cells before physical breast exams and mammograms, which tested negative (normal), could detect them. Both groups were given identical treatment and, after five years, the women whose cancer was detected by thermography lived longer. Screening thermograms increased survival by 61 percent.

Increased Accuracy

Another distinguishing difference between thermography and mammography is its accuracy. Mammograms correctly diagnose cancer only three percent of the time, according to a Harvard study published in the New England Journal of Medicine. In contrast, studies have shown that thermograms are highly sensitive and specific. (Sensitivity is the percentage of accurate positive results and specificity is percentage of accurate negative results.) A review of 15 large-scale studies published in the International Journal of Thermal Sciences concluded that breast thermography had an average sensitivity and specificity of 90 percent. Some studies have found sensitivity as high as 98 percent and specificity as high as 94 percent. With false positive rates of 10 percent on average, and as low as two percent, thermography is significantly more accurate than mammography, which has false positive rates as high as 97 percent.

Thermograms are notably more accurate in individuals who have large breasts, because excessive amounts of tissue can make mammograms difficult to read, and those who have dense breasts, common in younger women. For those who have a higher risk of developing breast cancer, thermography makes starting screening at earlier ages not only safer, but also much more effective.

The Bottom Line

Research has shown that abnormal thermograms are the most important indicators in predicting the development and recurrence of breast cancer. Experts even estimate that they are up to 10 times more significant than family history (having a mother, sister or daughter diagnosed with the disease). Because thermograms are painless, noninvasive, reliable and free of side effects, this alternative to screening mammography should be made available to all women.

References

Fletcher SW and Elmore JG. Mammographic Screening for Breast Cancer. New England Journal of Medicine, 348(17):1672-1680, 24 Apr 2003.

Gautherie M. Thermobiological assessment of benign and malignant breast diseases. American Journal of Obstetrics and Gynecology, 147(8):861-9, 15 Dec 1983.

Gros C and Gautherie M. Breast Thermography and Cancer Risk Prediction. Cancer, 45:51-56, 1980.

Haberman J. The present status of mammary thermography. CA: A Cancer Journal for Clinicians, 18: 314-321,1968.

Louis K, Walter J and Gautherie M. Long-term assessment of breast cancer risk by thermal imaging, Biomedical Thermology, Alan R. Liss, Inc. pp. 279-301, 1982.

Ng EY-K. A review of thermography as promising non-invasive detection modality for breast tumor. International Journal of Thermal Sciences, 48(5):849-859, May 2009.

Ng EY et al. Computerized detection of breast cancer with artificial intelligence and thermograms. Journal of Medical Engineering and Technology, 26(4):152-7, Jul-Aug 2002.

Stark  A and Way S. The Screening of Well Women for the Early Detection of Breast Cancer Using Clinical Examination with Thermography and Mammography. Cancer, 33:1671-1679, 1974.

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