The aim of this study was to investigate whether the temperature difference between a malignant (or benign) tumor and the armpit (AT) could be used as a criterion in the diagnosis of the tumor malignancy. In our study, we measured the temperature of tumors beneath the skin with a needle thermocouple, which causes minimal discomfort or pain to the patients. In principle, the temperature of a tumor should be compared with the temperature of normal tissue surrounding the tumor. To avoid these disadvantages, we compared tumor temperature with armpit temperature as it is relatively stable and is easily measured. Thermography has been extensively used as a cancer detection tool but has not been accepted for routine application.