Differentiating benign tumor from malignant tumor using laser Doppler flowmetry

Laser Doppler flowmetry is an important tool for the measurement of the microcirculatory blood flow. It is based on the principle of the Doppler shift. The instrument gives the blood flow in terms of arbitrary units known as perfusion units, which is nothing but the product of number of moving blood cells and their mean velocity. Though it is not an absolute value, perfusion units are linearly related to blood flow in the microcirculation. We used this method to study the effect of temperature on the skin blood flow. The selected area was the skin overlying malignant tumor and the skin overlying the benign tumor. Since this study was carried out at one site, spatial variation in the perfusion is eliminated. The response was studied as the temperature-perfusion index, i.e. the ratio of the perfusion at the higher temperature to the perfusion at the basal temperature. This was done to minimise inter individual variations in normal microcirculation at the basal level. Our study shows that the skin overlying malignant tumor responds poorly to thermal stress compared to the skin overlying breast cancer patients with benign tumor