Effects of hyperthermia on normal and tumor microenvironment.

Abstract
The effects of hyperthermia [for cancer therapy] on pH, local blood flow (LBF) and tissue oxygen tension (TpO2) in several normal and tumor tissues [human tumors and mouse mammary adenocarcinoma C3H cells] were studied. TpO2, LBF and pH apparently are inhomogeneous in tumor tissue. TpO2 is very low in certain areas which also seem deprived of blood flow and are at very low pH. Hyperthermia has a dual effect. At temperatures below 41.degree. C, it increases blood flow and TpO2; above 41.degree. C, it causes a collapse in blood flow, lower TpO2 and a shift of the tissue pH towards acidosis from the already low pH values found in tumors.