Antitumor effect of new local hyperthermia using dextran magnetite complex in hamster tongue carcinoma.

OBJECTIVE: This study was performed to clarify the usefulness of Dextran magnetite (DM) for the oral cancer hyperthermia. METHODS: Tumors were induced in golden hamster tongue by 9,10-dimethyl 1-1,2-benzanthracene (DMBA) application. DM suspension was locally injected into the tumor-bearing tongue and tongues were heated up to 43.0–45.0°C, by AC magnetic field of 500 kHz. RESULTS: The average time taken for the temperature to rise to 43.0°C or above was 162 s (n = 17) at the margin of the tumor and 420 s (n = 17) at the center of the tumor. According to the tumor volume, the time required for an increase in the central temperature of tumor to 43.0°C tended to be prolonged. Both temperatures could be maintained at approximately 43.0–45.0°C for 30 min. The inhibition of the growth of tongue carcinoma in the four-time heating group was significantly greater than in the control group (P < 0.01). Moreover, the survival rate was significantly higher in the heated groups than in the control group (P < 0.01). Histological examination revealed a brown uniform DM accumulation at the stroma in the margin of the tumors. Many of tumor cells disappeared at the site adjacent to this accumulation. CONCLUSION: These results strongly suggest the usefulness of this local hyperthermic system in the oral region that is accessible to this treatment.