Changes in tumor oxygenation after localized microwave heating

Upon heating at 40 degrees C for 30 min, the oxygenation of the tumor tissue significantly improved compared with control conditions at 35 degrees C. In contradistinction to this, the tumor oxygenation significantly decreased directly after 43 degrees C hyperthermia. A further temperature rise to 45 degrees C caused the oxygenation to drop drastically because of a severe restriction of nutritive blood flow. The changes in tumor oxygenation during hyperthermia seem to be predominantly mediated through changes in tumor blood flow, which showed the same directional changes.