Hyperthermia and local anesthetics: potentiation of survival of tumor-bearing mice.

Lidocaine infusion of a CA755 mammary adenocarcinoma growing in the hind leg of BDF1 mice results in a significant increase in the animals' survival when combined with heating for 1 hour in a 43.5 degrees C water bath. This ability of local anesthetics to prolong survival following hyperthermia is consistent with the hypothesis that increases in membrane fluidity influence sensitivity to heat. In view of the extensive clinical experience with local anesthetics, the delay between clinical application and the observation that they potentiate the action of hyperthermia in animals may be reduced.