http://www.drnudelman.ca/news.htm

Breast THERMOGRAPHY detects patterns of heat emitted from increased circulation, due to abnormal metabolic activity in cancer cells. Thus, THERMOGRAPHY is a physiological test.

Info from a Canadian site: http://sunleitehealth.ca/breastthermography.html

Excerpts:

Can thermography diagnose breast cancer?

No. Thermography, like mammography is a screening tool. Thermography identifies abnormal physiological changes in your breasts that may be cancerous. Mammography, a type of x-ray, identifies certain structures in the breast that can potentially be cancer. With both Mammography and Thermography, definitive diagnosis is done by other procedures such as a biopsy or lumpectomy.
Does thermography have the ability to show exactly where there is a tumor?

Thermography does not have the ability to pinpoint the location of a tumor for biopsy purposes. Consequently, for a comprehensive analysis, if indicated, an ultrasound and/or mammography are recommended to complement breast thermography if breast cancer is suspected.
Why do I need to do thermography when there are mammograms?

Current methods used to detect breast cancer depend primarily on the combination of both physical examination and mammography. While this approach has become the mainstay of early breast cancer detection, mortality from this disease has gone relatively unchanged for 40 years. Since the prevention of breast cancer has not become a reality as of yet, efforts must be directed at detecting breast cancer at its earliest stage, when there is the greatest potential for successful treatment. Consequently, the addition of breast thermography to the frontline of early breast cancer detection brings a great deal of good news for women.