Comparisons of the Suppressive Effects on Tumor Growth by Different Combinations of Administration of Arsenic Trioxide and Hyperthermia

Abstract

Arsenic trioxide (ATO), which is known to be an effective carcinostatic against acute promyelocytic leukemia (APL), has drawn attention throughout the world. Studies on the effectiveness of ATO against solid tumors have started, and progress is expected. In this study, we evaluate the differences in the suppressive effects on tumor growth between different combinations of ATO administration and hyperthermia. Mice in which a squamous cell carcinoma (SCC-VII) had grown to 5-7 mm in the right femoral region were subjected to experiments in 5 groups. The groups consisted of the control group, hyperthermia alone group, ATO alone group, A-H group (ATO administration followed by 1-hour hyperthermia at an interval of 2 hours), and H-A group (1-hour hyperthermia followed by ATO administration at an interval of 2 hours). In each group, 10 mice were used for the measurement of the tumor volume, and 1 mouse for the pathological examination. The suppressive effects on tumor growth were examined in the A-H and H-A groups using changes in the tumor volume and pathological findings of the tumor. The changes in the tumor volume demonstrated synergistic effects of combined hyperthermia and ATO administration, but there was no significant difference in the suppressive effects between the A-H and H-A groups. The histopathological examination demonstrated more histological changes in the