New modality of radiation therapy under increased tumor oxygen tension with angiotensin II: a pilot study

Elevation of the mean arterial blood pressure to approximately 150 mmHg by infusion of angiotensin II (AT II) resulted in a selective increase of blood flow in tumor tissue. A concomitant increase in tumor oxygen tension was also observed, suggesting the possibility of hyperbaric oxygenation radiation therapy. By controlling the infusion rate of AT II, mean blood pressure was increased up to 1.5-fold of normotension, and radiation was given (AT II-RT). Forty-one patients with recurrent tumors after intensive radiation therapy or with locally far advanced tumors were treated. Using an uneven dose fractionation scheme, total dose ranged from 5,100 to 7,800 cGy. The radiation response to the tumor was quite good. Including three complete responders, more than 50% tumor regression was obtained in 24 patients (58.5%), less than 50% in 13 (31.7%) and no effect in four (9.7%). On the other hand, damage to normal tissue was minimal, and no serious morbidity was experienced. For example, comparing the results in the two groups of lung cancer patients treated with or without AT II, superiority of AT II-RT was indicated. The curative ability of AT II-RT will be investigated further.