Breast cancer is the commonest cause of cancer death in women worldwide, and its incidence has been increasing for many years in economically developed countries. Differential scanning calorimetry (DSC) is more and more often applied for oncological purposes, as it could be used as a new method for diagnose and monitoring tumours. In current research liquid plasma components was detected with DSC in breast cancer patients. The study included 19 women with different tumour diameter (0.5-75 mm) and with or without regional lymph node metastases (0-10 metastatic lymph node). Preoperatively peripheral blood samples were collected from the patients and from healthy controls, and plasma components were analysed by DSC technique. The diameter of the tumour tissue and the number of metastatic lymph nodes were evaluated on the basis of postoperative histological results. In our preliminary study we observed thermic changes (e.g. T(m), calorimetric enthalpy) in the blood plasma of breast cancer patients, and we have found correlation with tumour size and with the degree of regional lymph node invasion as well. Further studies are needed to clarify these relationships, but our application of the DSC method has provided a potential tool for the early diagnosis and monitoring of breast cancer patients. (C) 2011 Elsevier B.V. All rights reserved.