Changes in tissue oxygenation and acidity induced by localized microwave hyperthermia and hematoporphyrin phototherapy, an update.

Changes in tumor tissue oxygenation and acidity were determined using ultramicroelectrodes, and presented in histogram fashion. The effect of Hyperthermia and Hpd photo-therapy were tested. It was found that both modalities affect tumor microcirculation, causing a marked drop in oxygen availability. Tissue pH is decreased by Hyperthermia, but not by phototherapy. These effects are long lasting, at least for 24 hours after treatment.