Effects of cytostatic drugs and 40.5 degrees C hyperthermia on human clonogenic tumor cells.

A tumor colony-forming assay was used to investigate the effect of 40.5 degrees C hyperthermia and drugs on the colony-forming ability of human clonogenic tumor cells. In order to be able to perform repeated incubations with identical tumor material, specimens were used that were augmented in the nude mouse system. Five tumor samples (two malignant melanomas, two squamous cell carcinomas of the lung and one small cell carcinoma of the lung) were incubated with seven drugs: doxorubicin, actinomycin-D, bleomycin, melphalan, vincristine, vinblastin and cisplatinum. One additional tumor specimen (chondrosarcoma) was incubated with doxorubicin immediately after resection. The incubation with drugs at 37 degrees C revealed dose response curves typical for each tumor. Incubation at 40.5 degrees C for 2 hr showed enhanced drug effects in five out of the six tumors tested. The drugs, with an enhanced effect and the pattern of enhancement were different in each individual tumor.