[Combined cell killing effects of anticancer drugs and hyperthermia in vitro]

Using an in vitro colony forming assay system, cytotoxic effects of anticancer drugs, adriamycin (ADM) and peplomycin (PEP), and the combined effect of hyperthermia and anticancer drugs on cultivated KK-47 cells were investigated. From the response curves obtained at 42 and 43 degrees C hyperthermia, 20% growth inhibition time (IT20) at 42 and 43 degrees C hyperthermia and 50% growth inhibition time (IT50) at 43 degrees C were calculated. The IT20 and IT50 hyperthermia were combined with a 2-hour treatment of each of the anticancer drugs. When the hyperthermia was combined with various concentrations of ADM ranging from 0.005 to 0.1 microgram/ml, enhanced cell killing effects were obtained at the concentrations of less than 0.02 microgram/ml of ADM, whereas, there was no increase in cell killing effect at the concentrations of more than 0.05 microgram/ml of ADM. The combination of hyperthermia with PEP considerably enhanced the cell killing effects with an increase of PEP concentration.