[Biological basis of thermochemotherapy].

Interactive effects of combined treatment with hyperthermia and chemotherapeutic agents or chemical substances were interpreted in the experimental aspects of medical sciences. It was also interpreted how a physiological circumferential conditions in vivo influenced on thermosensitivities of cells, tissues or individuals. Among the physiological conditions, hypoxia and insufficient nutrition apparently enhance thermosensitivity while reduce radiosensitivity. Interactive effects in combined treatments with hyperthermia and alkylating agents varies among the alkylating agent adopted. DNA strand scission by alkylating agent is increased and repair of the DNA damage is suppressed in combination with hyperthermia. Almost all the antimetabolites and botanic alkaloids are reported to show no appreciable interactive effect in combination with hyperthermia. However, a sort of derivatives of mitotic toxins interacts with hyperthermia (unpublished data). Effects of anticancer antibiotics vary due to the variety of the mechanism of action of the antibiotics. Therefore, interactive effects of these antibiotics with hyperthermia also vary among the antibiotics. Most marked interaction with hyperthermia was shown in Mitomycin C, while the cell killing effect of Actinomycin D itself was reduced reportedly by the combined hyperthermia. Further development in thermophysiology may perform an extent of elevation in human whole body temperature. It has been considered internal heating may be more efficient than external heating for the hyperthermia alone. In the other hand, local heating can chemosensitize within the localized heated area where the blood concentration of anticancer drug is even, although variety of intervention could be devised to localize anticancer drug distribution. Variety of heating modalities and the apparatus would be developed which contribute for further interdisciplinary oncotherapy in near future.