A basic in vitro study on effective conservative combined therapy for malignant tumors

The study aimed to clarify the antitumor effects of radiotherapy, chemotherapy, hyperthermia, and combinations thereof in an effort to devise a highly effective noninvasive regimen. The human KB cell line, derived from an epidermal carcinoma of the mouth, was used for the experiments. The antitumor effects of monotherapy—with radiotherapy of 6-MV X-rays, 43°C hyperthermia, and chemotherapy with the taxoid antineoplastic drug docetaxel—as well as combinations of these therapies were evaluated using a colony assay. Compared with monotherapy of 6-MV X-rays, 43°C heat, and docetaxel, radiation combined with 43°C heat showed a slight increase in sensitization; radiation or 43°C heat combined with docetaxel showed stronger sensitization. Furthermore, more pronounced sensitization was observed with a three-way combination of radiation, 43°C heat, and docetaxel. These results suggest that the combined use of radiation, 43°C heat, and docetaxel will improve the therapeutic efficacy against malignant tumors by increasing sensitization to the antitumor effects of each therapy. The results also suggest that it is possible to reduce the dosage of the individual therapies in combination therapy.