The response of skin microcirculation to hyperthermic stress in tumour patients

Hyperthermia and its effect on tissues are topics of great interest to scientists working in the area of radiation biology and medicine. It has been shown by many workers, that blood flow in malignant tissue displays a different response to heating than that in normal tissue. Initially, the blood flow in tumour tissue is greater than that in normal tissue, and when heat is applied there is an increase in blood flow. The extent of the increase in flow with increasing temperature is greater in normal tissue than in tumour tissue. In our laboratory we studied the effect of temperature on skin blood flow. The skin overlying tumour tissue was compared with skin with no underlying abnormality in cancer patients, and with the skin in healthy control subjects. The instrument used was a Laser Doppler Perfusion Monitor, Pf3 (Perimed, Stockholm, Sweden). We found that the skin overlying tumour tissue showed higher basal perfusion than the skin at the contralateral site with no underlying abnormality. The skin above tumour tissue showed a reduced perfusion response to an increase in temperature (vascular sluggishness) compared to skin at the contralateral site and skin in healthy controls. The reduction in thermal response depends on the size of the tumour.